MATRIZ EXTRACELULAR X CORACAO/MIOCARDIO

Au: Panizo A; Pardo J; Hern ndez M; Galindo MF; Cenarruzabeitia E; D¡ez J.

Ad: Department of Pathology, University Clinic, School of Medicine, Pamplona, Spain.

Ti: Quinapril decreases myocardial accumulation of extracellular matrix components in

spontaneously hypertensive rats.

So: Am J Hypertens; 8(8):815-22, 1995 Aug.

Ab: In genetic and acquired hypertension, a structural remodeling of the nonmyocyte

compartment of myocardium, including the accumulation of fibrillar collagen and other

components of the extracellular matrix (ECM) within the interstitium, represents a

determinant of pathologic hypertrophy that leads to ventricular dysfunction. Therefore, to

evaluate the potential benefit of the angiotensin converting enzyme (ACE) inhibitor

quinapril in reversing the interstitial remodeling in spontaneously hypertensive rats (SHR)

with established left ventricular hypertrophy (LVH), we treated 16-week-old male SHR

with oral quinapril (average dose, 10 mg/kg body weight/day) for 20 weeks. Interstitial

fibrosis was determined morphometrically using an automatic image analyzer. The amount

of collagen was evaluated by measuring myocardial hydroxyproline concentration.

Myocardial deposition of collagen molecules (types I, III, and IV) and other ECM

components (fibronectin, laminin) was analyzed by immunohistochemical techniques using

specific monoclonal antibodies. The activity of ACE was measured in left ventricular tissue

by a fluorometric assay. In quinapril-treated SHR compared with 36-week-old untreated

SHR and age- and sex-matched Wistar-Kyoto (WKY) controls, we found 1) a lesser degree

of LVH and a lesser level of blood pressure, 2) a lesser degree of interstitial fibrosis,

represented by less interstitial collagen volume fraction (5.73 +/- 0.45% v 3.42 +/- 0.28%, P

< .05; WKY, 3.44 +/- 0.66%), 3) a lower hydroxyproline concentration (1.09 +/- 0.05

mumol/L/g dry weight/100 g body weight to 0.81 +/- 0.05 mumol/L/g dry weight/100 g

body weight, P < .05; WKY, 0.96 +/- 0.06 mumol/L/g dry weight/100 g body weight), 4) a

lesser presence of collagen fibers, and 5) a lesser presence of collagen IV, fibronectin, and

laminin.(ABSTRACT TRUNCATED AT 250 WORDS) (Au).

Au: He Q; Spiro MJ.

Ad: Department of Medicine, Harvard Medical School, Boston, MA, USA.

Ti: Isolation of rat heart endothelial cells and pericytes: evaluation of their role in the

formation of extracellular matrix components.

So: J Mol Cell Cardiol; 27(5):1173-83, 1995 May.

Ab: In order to facilitate investigation of the cells responsible for overproduction of type VI

collagen in the extracellular matrix surrounding the capillaries of diabetic rat myocardium,

procedures have been developed for the isolation from this tissue of endothelial cells as

well as a cell type identified as pericytes. This was accomplished by enzymatic and

mechanical disruption of ventricles from young rats (125 g) followed by removal of

myocytes through their nonadherence to tissue culture surfaces. Endothelial cells were

separated by fluorescence-activated cell sorting after staining with rhodamine-labeled

acetylated low density lipoprotein and were identified by their monolayer growth pattern,

reaction with anti-von Willebrand factor and the ability to form capillary-like tubes

induced by low serum concentration. Pericytes were purified by selective scraping for

removal of other cell types and were identified by their irregular shape, overlapping growth

pattern at confluence, reaction with anti-smooth muscle actin and content of GLUT4

glucose transporter. Fibroblasts, visualized after staining with rhodamine-labeled alpha 2-

macroglobulin, were only rarely detected. Analysis of collagen by immunoblotting

indicated formation by both cell types of alpha 1(IV) collagen as well as the three subunits

of type VI (alpha 3 at 205 kDa and alpha 1 plus alpha 2 at 150 kDa). Both endothelial cells

and pericytes demonstrated transcripts for types VI, IV and I collagen, as well as

fibronectin, but while the level of the mRNA for type IV collagen was higher in pericytes

than in endothelial cells, the reverse was true for collagens VI and I and fibronectin. These

observations suggest that both endothelial cells and pericytes contribute to formation of the

myocardial capillary matrix, but that changes involving only type VI collagen, such as occur

in diabetic cardiomyopathy, may reflect a response primarily of endothelial cells (Au).

Au: Hsueh WA; Do YS; Anderson PW; Law RE.

Ad: Department of Medicine, University of Southern California, School of Medicine, Los

Angeles 90033, USA.

Ti: Angiotensin II in cell growth and matrix production.

So: Adv Exp Med Biol; 377:217-23, 1995.

Ab: Glomerular mesangial cells and cardiac fibroblasts have been called ®myofibroblasts®

because of their phenotypic characteristics (resembling both the fibroblast and muscle

cells). Thus, it is not surprising that AII would have similar effects on both cell types, which

play critical roles in target organ stress response and wound healing, ultimately leading to

remodeling changes. These effects are primarily mediated by the AT1 receptor and include:

1) growth: hyperplasia in cardiac fibroblasts and hypertrophy in normal adult mesangial

cells and 2) matrix production: there appears to be an early upregulation of fibronectin

message which is later followed by an increase in collagens. It is likely that elevated

production of fibronectin may activate signal transduction pathways which lead to increased

expression of collagen genes, and which may be critical for the organization and laying

down of collagens. Thus, an overall theme that emerges is the impact of AII on both growth

and wound repair. Other potential important cellular effects of AII in these systems

include: 1) stimulation of growth factors, cytokines, and arachidonic acid products that

could have autocrine or paracrine effects, 2) regulation of cell migration and adhesion, 3)

alteration of responses to neurohormones, 4) development and maintenance of a

differentiated phenotype, and others. Molecular techniques including subtraction

hybridization, differential display, antisense knockout, and development of transgenic

and embryonic stem cell models will be important in defining the specific role of AII in

cardiovascular and renal disease (Au).

Au: Nogami K; Kusachi S; Niiya K; Moritani H; Tsuji T.

Ad: First Department of Internal Medicine, Okayama University Medical School, Japan.

Ti: Changes in extracellular matrix components in cardiomyopathic Syrian hamster, BIO

14.6.

So: Jpn Circ J; 59(9):631-40, 1995 Sep.

Ab: We examined changes in the distribution of extracellular matrix components in the

myocardium of cardiomyopathic Syrian hamsters (BIO 14.6). Fibronectin, laminin, and type

IV collagen, and type I and III collagens were immunohistochemically stained by the

avidin-biotin-peroxidase complex method, using a polyclonal antibody for each component.

Hearts obtained from 4 stages of BIO 14.6 cardiomyopathy were examined. Peri- and

endomysial fibrosis increased as the disease progressed. Replacement and meshwork

(perimysial fibrosis penetrating the intercellular space) fibrotic lesions appeared beginning

in the 2nd stage, ie, the fibrotic and healing stage. All of the components examined, ie,

fibronectin, laminin and type IV collagen, and type I and III collagens, were present in

various fibrotic lesions and played a significant role in fibrotic changes throughout all of the

stages of the disease. No primary deficit of any of these components was seen. An increased

distribution of fibronectin was observed in both the enlarged peri-and endomysial spaces

beginning in the initial stage, ie, the necrotic stage, when myocyte hypertrophy was

inconspicuous, and distribution throughout the myocardium increased further as the disease

progressed. Laminin and type IV collagen in the fibrotic lesions were not restricted to the

myocyte membrane. Type III collagen was distributed in replacement and meshwork

fibrotic lesions, and the extent of its distribution increased in proportion to that of type I

collagen. The continuous increases in the distribution of fibronectin, laminin and type III

collagen indicate that fibrotic changes occurred continuously in this model.(ABSTRACT

TRUNCATED AT 250 WORDS) (Au).

Au: Thieszen SL; Rosenquist TH.

Ad: Department of Pathology and Microbiology, University of Nebraska Omaha, USA.

Ti: Expression of collagens and decorin during aortic arch artery development: implications

for matrix pattern formation.

So: Matrix Biol; 14(7):573-82, 1995 Jul.

Ab: The elastic matrix of the large arteries shows a high level of spatial order. However, the

mechanisms by which such order is established and maintained are largely unknown. The

embryonic development of the avian heart and great vessels provides an appropriate model

to investigate these mechanisms. In control embryos, an elastic matrix with a high level of

spatial order develops in the nascent great vessels. But after the normal vascular smooth

muscle (VSM) progenitor cells in the great vessels are experimentally replaced by other

VSM progenitor cells, the elastic extracellular matrix is congenitally disordered. The

present study used this model to test the hypothesis that the proteoglycan decorin was

involved in the establishment and maintenance of the normal three-dimensional spatial

order of the vascular elastic matrix. The temporospatial expression of decorin was analysed

during development of normal vessels and in experimental vessels with surrogate VSM.

The results showed the following: (1) the expression of decorin was related in time and

space to the establishment of large helical collagen type III fibers that are characteristic of

the normal elastic extracellular matrix; (2) in the experimental extracellular matrix there

were few helical fibers of collagen type III, but those that were present remained positive

for decorin; and (3) in both control and experimental vessels, decorin associated with

neither fibers of collagen type I nor fibers of collagen type III in any conformation other

than the large helical fibers. These data indicate a previously unrecognized relationship

between decorin and the spatial order of the physiologically significant helical fibers of

collagen type III (Au).

Au: Rebres RA; McKeown-Longo PJ; Vincent PA; Cho E; Saba TM.

Ad: Department of Physiology and Cell Biology, Albany Medical College, New York

12208, USA.

Ti: Extracellular matrix incorporation of normal and NEM-alkylated fibronectin: liver and

spleen deposition.

So: Am J Physiol; 269(6 Pt 1):G902-12, 1995 Dec.

Ab: The incorporation of plasma fibronectin (pFn) into the extracellular matrix (ECM) is

believed to influence tissue integrity, wound repair, and vascular permeability. In vitro,

matrix assembly of Fn requires the binding of soluble Fn to cell-associated matrix assembly

sites. Alkylation of human pFn (HFn) with N-ethylmaleimide (NEM) prevents the initial

binding of Fn to matrix assembly sites as well as its in vitro incorporation into the ECM as

reflected by detergent-insoluble 125I-labeled Fn (pool II Fn). We determined the kinetics of

Fn matrix incorporation in tissue and whether NEM treatment of rat pFn (NEM-RFn)

would limit its in vivo incorporation into ECM by analysis of pool I [deoxycholate (DOC)

soluble] and pool II (DOC insoluble) 125I-Fn in tissues after its intravenous injection into

rats. After intravenous injection, tissue incorporation of normal rat 125I-pFn was especially

intense in liver and spleen, in agreement with the large amount of endogenous Fn detected

in the matrices of these organs. Tissue deposition of plasma-derived 125I-RFn in liver and

spleen peaked by 4 h, with significant (P < 0.01) loss over 24 h, indicating turnover of

matrix Fn. Tissue localization of normal 125I-RFn in liver, lung, spleen, heart, and intestine

was greater (P < 0.05) than 125I-NEM-RFn at 4 h. Normal HFn, but not NEM-HFn, was

incorporated into tissues and colocalized with endogenous Fn in the matrix. To identify the

cells mediating the intense incorporation of pFn into liver ECM, we compared matrix

assembly of 125I-HFn by cultured fibroblasts, hepatocytes, and hepatic Kupffer cells. With

fibroblasts, 125I-HFn in pool I reached steady state by 3 h, whereas 125I-HFn in pool II

exceeded that in pool I by 6 h and continued to increase over 24 h. With hepatocytes, pool I

125I-HFn reached steady state by 1 h, and a progressive increase (P < 0.05) of 125I-HFn in

pool II was observed over 24 h. Kupffer cells were not able to incorporate significant

amounts of 125I-HFn into matrix. NEM-HFn displayed limited incorporation into ECM by

both fibroblast and hepatocyte cultures. These novel observations suggest that the

interaction of soluble pFn with matrix assembly sites is necessary to its in vivo

incorporation into the ECM (Au).

Au: Tsuda T; Philp N; Zile MH; Linask KK.

Ad: Division of Cardiology, Children's Hospital of Philadelphia, University of

Pennsylvania School of Medicine 19104, USA.

Ti: Left-right asymmetric localization of flectin in the extracellular matrix during heart

looping.

So: Dev Biol; 173(1):39-50, 1996 Jan 10.

Ab: The early embryo is initially bilaterally symmetrical. One of the first distinct

indications of asymmetry in the embryo occurs during heart looping. The midline tubular

heart begins to bend to the right to form a C-shaped structure around 30 hr of development

in the avian model. A molecular basis for heart asymmetry and direction of looping is not

known, although factors inherent to the myocardium are believed to underlie looping. A

left-right asymmetric localization of a specific molecule in the bilateral heart forming

regions has not been reported previously. One molecule that we are calling flectin (flectere,

in L., to bend or to loop) shows a bilateral asymmetric localization early in the heart

forming mesoderm and continues to be expressed asymmetrically in a highly organized

manner in the cardiac jelly during heart looping. This large extracellular matrix molecule

has been identified using a monoclonal antibody F-22 (Mieziewska et al., 1994a,b). Flectin

shows a discrete spatiotemporal pattern of extracellular matrix expression during avian

heart development. An asymmetric expression of flectin is observed during heart

development at stage 7+/8- (approximately at 24 hr of development around the 3-somite

stage). It is predominantly expressed in the left precardiac mesoderm at this

developmental period. Between stages 12 and 14, flectin continues to be asymmetrically

expressed in the myocardium and is localized at high levels on the basal side of the

myocardium and within the cardiac jelly extending to the endocardial cell surfaces. In the

same plane of the looping part of the heart it is differentially organized within the cardiac

jelly on the convex side and in the outer loop areas. A reduced expression is apparent

anteriorly and posteriorly along the tubular heart. The initial asymmetry of localization is

maintained throughout the tubular heart. At stage 22 (Embryonic Day 3.5), intensity of

immunolocalization of flectin is significantly decreased, with left-right asymmetry

becoming less discernible or absent. It again is expressed in Day 10 embryonic hearts.

Flectin expression appears to be modulated by retinoids. In vitamin A-deficient quail

embryonic hearts that do not loop (Dersch and Zile, 1993; Twal et al., 1995), flectin protein

expression is decreased and disorganized, as are other extracellular matrix components

comprising the cardiac jelly (Au).

Au: Schaper J; Mollnau H; Hein S; Scholz D; M�nkel B; Devaux B.

Ad: Max-Planck-Institut, Abt. f�r Exp. Kardiologie, Bad Nauheim.

Ti: Wechselwirkungen zwischen Kardiomyozyten und der extrazellul„ren Matrix im

insuffizienten menschlichen Herzen. / Interactions between cardiomyocytes and

extracellular matrix in the failing human heart.

So: Z Kardiol; 84 Suppl 4:33-8, 1995.

Ab: Numerous morphological changes can be observed in human myocardium failing

because of dilated cardiomyopathy. These can be observed by electron microscopy and by

immunofluorescence microscopy using monoclonal antibodies. These changes include: 1)

the occurrence of hypertrophied and atrophied myocytes as well as cells of normal size, 2)

degenerative changes in myocytes; these consist of nuclei of varying size and shape, lack of

contractile material, disorganization of the cytoskeleton, and sequestration of cellular

particles into the extracellular space and 3) an enlarged extracellular space, that is, fibrosis,

which contains increased amounts of the different matrix proteins such as fibronectin and

laminin, the various collagens, and chondroitin sulfate, in addition to cellular debris and

numerous macrophages and fibroblasts. On the basis of these findings it is hypothetized that

there exists an interaction between myocytes and the extracellular matrix. The cells of the

latter may be stimulated to higher rates of proteins synthesis by the presence of cellular

debris. This process, in turn, may be harmful for the structural integrity of myocytes which

consequently sequester more cellular particles. In this manner, a vicious circle may be

started that leads to further structural and functional deterioration of the myocardium,

finally resulting in failure (Au).

Au: Violaris AG; de Jong M; MacLeod DC; Umans VA; Verdouw PD; Serruys PW.

Ad: Catheterisation Laboratory, Thoraxcenter, Erasmus University Rotterdam, The

Netherlands.

Ti: Increased extracellular matrix synthesis by smooth-muscle cells obtained from in vivo

restenotic lesions by directional coronary atherectomy.

So: Am Heart J; 131(3):613-5, 1996 Mar.

Au: Lui K; Jackson M; Sowa MG; Ju H; Dixon IM; Mantsch HH.

Ad: Institute for Biodiagnostics, National Research Council Canada, Winnipeg, Manitoba.

Ti: Modification of the extracellular matrix following myocardial infarction monitored by

FTIR spectroscopy.

So: Biochim Biophys Acta; 1315(2):73-7, 1996 Mar 1.

Ab: Comparison of mid- and near-infrared spectra of control and infarcted rat ventricular

tissue reveals the presence of absorptions in infarcted tissue which are highly characteristics

of collagen, indicating large scale deposition of type I collagen in the myocardium

following infarction. These results demonstrate that IR spectroscopy may be used to rapidly

monitor the modifications of the extracellular matrix associated with myocardial infarction

(Au).

Au: Stetler-Stevenson WG.

Ad: Extracellular Matrix Pathology Section, National Cancer Institute, National Institutes

of Health, Bethesda, Maryland 20892, USA.

Ti: Dynamics of matrix turnover during pathologic remodeling of the extracellular matrix

[comment].

Cm: Comment on:/Am J Pathol/1996 May;148(5):1639-48.

So: Am J Pathol; 148(5):1345-50, 1996 May.

Au: Rhoads ML; Fetterer RH.

Ad: Parasite Biology and Epidemiology Laboratory, United States Department of

Agriculture, Beltsville, Maryland 20705, USA.

Ti: Extracellular matrix degradation by Haemonchus contortus.

So: J Parasitol; 82(3):379-83, 1996 Jun.

Ab: To better understand the in vivo function of secreted cysteine proteases of Haemonchus

contortus, the ability of live parasites to degrade connective tissue was investigated using

[3H]proline-labeled extracellular matrix produced by smooth-muscle cells (R22). The

matrix was composed of glycoprotein(s) (34%), elastin (49%), and collagen (15%) in an

insoluble, multilayered, cross-linked structure. No degradation of the extracellular matrix

by third-stage larvae (L3) (10,000/ml) occurred during 24-hr in vitro incubation. In contrast,

fourth-stage larvae (L4) (1,000/ml) degraded 42% of the matrix, whereas adults (100/ml)

degraded the entire matrix. The presence of Z-phe-ala-FMK (100 microM), a specific

cysteine protease inhibitor, during incubation of adults, reduced matrix degradation to

30% without affecting parasite motility. Isolated adult excretory/secretory products (ESP)

(0.1 mg protein/ml) degraded 64% of the total matrix; specific degradation consisted of

80.3% of the glycoprotein, 67.1% of the elastin, and 27.6% of the collagen matrix

components. Degradation of the matrix by ESP was stimulated by dithiothreitol (2 mM) and

inhibited by Z-phe-ala-FMK. Thus, the secretory cysteine proteases of H. contortus are

active under physiological conditions and able to degrade the major components of

connective tissue in an in vitro model system that simulates their structure in vivo. These

data strengthen the proposed role of these enzymes in the breakdown of host tissue (Au).

Au: Riessen R; Wight TN; Pastore C; Henley C; Isner JM.

Ad: Department of Medicine (Cardiology), St. Elizabeth's Medical Center, Tufts University

School of Medicine, Boston, MA 02135, USA.

Ti: Distribution of hyaluronan during extracellular matrix remodeling in human restenotic

arteries and balloon-injured rat carotid arteries.

So: Circulation; 93(6):1141-7, 1996 Mar 15.

Ab: BACKGROUND: The glycosaminoglycan hyaluronan (HA) is present in developing

tissues and healing wounds and forms a loose, hydrated extracellular matrix (ECM) that

promotes processes such as cell migration. To investigate the potential contribution of HA

to the pathogenesis of restenosis, we studied (1) human lesions obtained by directional

atherectomy and (2) experimentally induced neointima formation in balloon-injured rat

carotid arteries. METHODS AND RESULTS: A biotinylated proteoglycan fragment that

binds specifically to HA was used to stain atherectomy specimens from 29 human

restenotic lesions (mean restenosis interval, 6.0+/-4.4 months) and 8 human primary

lesions. The loose myxoid ECM typical of human restenotic arteries demonstrated intense,

diffuse staining for HA. The intensity was inversely related to the density of

immunostaining for collagen types I and III and was lowest in hypocellular primary

atherosclerotic plaque. Among 24 rat carotid arteries retrieved 3, 7, 14, 28, 42, or 56 days

after balloon injury and immunostained as well for proliferating cell nuclear antigen,

staining for HA in the neointima reached a maximum 7 days after balloon injury and was

associated with the presence of proliferating, PCNA-positive smooth muscle cells.

CONCLUSIONS: Hyaluronan is a characteristic constituent of the loose myxoid ECM in

human restenotic arteries and of the neointima in experimentally injured arteries. The

presence of hyaluronan may be a marker for an initial phase of the extracellular matrix

remodeling that occurs during the development of a fibroproliferative lesion and could

facilitate biological processes such as cell migration (Au).

Au: Kim SB; Kang SA; Park JS; Lee JS; Hong CD.

Ad: Department of Internal Medicine, University of Ulsan, Seoul, Korea.

Ti: Effects of hypoxia on the extracellular matrix production of cultured rat mesangial cells.

So: Nephron; 72(2):275-80, 1996.

Ab: Glomerular changes in patients with cyanotic congenital heart and chronic lung

diseases and in persons living at a high altitude might be related to hypoxemia. This study

was carried out to examine the effects of hypoxia on the extracellular matrix production by

cultured rat mesangial cells (CRMC). Subconfluent CRMC monolayers were grown with

10% oxygen (hypoxia) and 20% oxygen (control) for 1, 3, and 5 days. The production of

type IV collagen (CIV), fibronectin (FN), and laminin (LN) by CRMC was evaluated by

flow cytometry and immunofluorescent microscopy. Total RNA was extracted and

Northern blotting and hybridization were performed with cDNAs for CIV, FN, and LN. The

surface expression of CIV on FC was higher in hypoxia than under control conditions at

day 5 (158% of control). The surface expression of FN was also higher in hypoxia at day 3

(303%) and at day 5 (332%). The surface expression of LN was lower at day 1 (71%).

Immunofluorescent microscopy showed similar changes with flow cytometry. The mRNA

level for CIV and FN was maximal at day 5 with 206 and 305% of control, respectively.

Hypoxia had little effect on LN mRNA expression. These results show that hypoxia

stimulates the synthesis of extracellular matrix of cultured rat mesangial cells. Hypoxia may

contribute to the development of glomerular changes in cyanotic congenital heart diseases,

chronic lung diseases, and in persons living at a high altitude (Au).

Au: Gabler U; Berndt A; Kosmehl H; Mandel U; Zardi L; M�ller S; Stelzner A;

Katenkamp D.

Ad: Institute of Pathology, University of Jena, Germany.

Ti: Matrix remodelling in dilated cardiomyopathy entails the occurrence of oncofetal

fibronectin molecular variants.

So: Heart; 75(4):358-62, 1996 Apr.

Ab: OBJECTIVES: To investigate whether disturbance of the cellular homoeostasis and

integrity of cardiomyocytes in dilated cardiomyopathy (DCM) is accompanied by

alterations in cell-matrix relations as indicated by changes in the deposition of fibronectin

(FN) isoforms. DESIGN: Tissue from a case series of patients with DCM was investigated

by immunohistochemistry with antibodies against FN (all variants, clone IST4), ED-A+ FN

(clone IST9), ED-B+ FN (clone BC1), and oncofetal glycosylated FN (clone 5C10). The

sites of de novo synthesis of FN were demonstrated by means of non-radioactive RNA in

situ hybridisation (ISH) with biotinylated FN cDNA fragments as the probe. SETTING:

University hospital. PATIENTS: Samples from 10 patients with clinical criteria and

histological diagnosis of DCM and from 3 individuals with normal hearts.

INTERVENTIONS: Samples were obtained by right ventricular endomyocardial biopsy.

MAIN OUTCOME MEASURE: Distribution of oncofetal FN variants in DCM hearts.

RESULTS: Immunostaining of FN (IST4, all variants) showed a coarse interstitial network

in normal and diseased myocardium. ED-A+ FN was deposited as fine interstitial spots in

normal myocardium and in DCM samples. Immunostaining for oncofetal glycosylated FN

and ED-B+ FN was not seen in normal adult myocardium, whereas myocardium from DCM

patients showed focal and delicate staining in the interstitium. RNA ISH showed that these

deposits resulted from local FN synthesis. CONCLUSION: The results accord with de novo

expression of oncofetal FN variants in hearts from patients with DCM. The oncofetal FN

variants may serve as disease markers in myocardium affected by DCM (Au).

Au: Okada H; Kawaguchi H; Kudo T; Sawa H; Okamoto H; Watanabe S; Urasawa K;

Murakami T; Kitabatake A.

Ad: Department of Cardiovascular Medicine, Hokkaido University School of Medicine,

Sapporo, Japan.

Ti: Alteration of extracellular matrix in dilated cardiomyopathic hamster heart.

So: Mol Cell Biochem; 156(1):9-15, 1996 Mar 9.

Ab: The purpose of this study was to characterize the collagen in hereditary dilated

cardiomyopathic hamster hearts, and to examine the participation of the collagen in the

occurrence and progression of cardiomyopathy. BIO 53.58 hamsters (5, 10, 20 weeks old)

were used as the model of dilated cardiomyopathy. Flb hamsters were used as controls. The

collagen content was almost constant at any age in the Flb hamsters, but increased with age

in BIO 53.58 hamsters. Type III collagen increased significantly in BIO 53.58 hamsters at

10 weeks. The acetic acid solubility of collagen decreased in BIO 53.58 hamsters as the

fibrosis progressed, but was unchanged in controls. Reducible crosslinks showed a

tendency to decrease progressively in BIO 53.58 hamsters. There were no differences

between Flb and BIO 53.58 hamsters at 5 weeks, but its expression in BIO 53.58 hamsters

at 10 and 20 weeks of age increased compared to Flb controls. These findings indicate that

in the early phase of cardiomyopathy the extracellular matrix of the myocardium is rich in

type III collagen. In the later phase, the matrix resembles that of hard tissues, whose

collagen is mainly of type I collagen and is insoluble. These data suggest that the increased

collagen synthesis may impair the cardiac function in the development of

cardiomyopathy (Au).

Au: Schwartzkopff B; Mundhenke M; Strauer BE.

Ad: Medical Clinic, Heinrich-Heine-University D�sseldorf, Germany.

Ti: Remodelling of intramyocardial arterioles and extracellular matrix in patients with

arterial hypertension and impaired coronary reserve.

So: Eur Heart J; 16 Suppl I:82-6, 1995 Aug.

Ab: The heart in pressure overload is threatened by the development of diastolic and

systolic dysfunction even in the absence of coronary heart disease. In pressure overload,

systolic wall stress leads to an increase in left ventricular mass through hypertrophy of

myocytes. An activation of myocytic as well as non-myocytic cells is present. An increase

in interstitial collagen accompanies hypertrophy of the myocytes. Thus, myocytic

hypertrophy and fibrosis cause diastolic dysfunction early on, even when systolic function is

still well preserved. In hypertensive heart disease, the coronary microcirculation is

remodelled by thickening of the walls of intramyocardial arterioles in relation to their

lumen and by an increase in periarteriolar fibrosis. This remodelling of the intramyocardial

vasculature is combined with a reduction in coronary vasodilator reserve that may lead to

malnutrition and malperfusion of the hypertrophied myocytes. The combined processes of

myocytic hypertrophy, vascular remodelling and increased fibrosis may be important in the

process of ventricular dilatation and failure in hypertensive heart disease (Au).

Au: Tyagi SC; Kumar S; Borders S.

Ad: Department of Medicine, Dalton Cardiovascular Research Center, University of

Missouri-Columbia 65212, USA.

Ti: Reduction-oxidation (redox) state regulation of extracellular matrix metalloproteinases

and tissue inhibitors in cardiac normal and transformed fibroblast cells.

So: J Cell Biochem; 61(1):139-51, 1996 Apr.

Ab: Latent matrix metalloproteinases (MMPs) in normal myocardium are activated in end-

stage heart failure. In vitro oxidized glutathione (GSSG) activates myocardial MMPs which

contains a cysteine residue. In vivo GSSG induce the collagen lysis and cardiac dilatation.

To assess whether thiol and non-thiol reducing agents have direct effect on the interstitial

human heart fibroblast (HHF) proliferation and MMP expression, HHF and polyoma virus

transformed fibroblast cells were cultured with or without the thiol-containing reduced

(GSH) or oxidized (GSSG) glutathiones, pyrrolidine dithiocarbamate (PDTC) and N-

acetylcysteine (NAC), and non-thiol ascorbic acid. After 100 micrograms/ml

(approximately 0.3 mM) GSH or PDTC treatment the proliferative (synthetic) phenotype of

transformed fibroblast cells was changed to quiescent (contractile) phenotype. Also, after

GSH, PDTC, and ascorbic acid treatment the medium was then analyzed for MMP activity

by zymography. The results indicate reduction in MMP expression in transformed fibroblast

cells after GSH and PDTC treatments and no effect after ascorbic acid treatment. Based on

reverse zymography, we observed the level of tissue inhibitor of metalloproteinase (TIMP)

at a decreased level in transformed cells. The effect of the reducing agent at the gene

transcription was measured by estimating mRNA (Northern blot analysis) of MMP and of

TIMP in the cells that were cultured in medium in the presence and absence of GSH. These

results indicate that GSH induces MMP-2 and MMP-1 expression in normal HHF and

that GSH reduces MMP-2 and MMP-1 in transformed fibroblast cells. After the treatment,

the TIMP-2 level was repressed in normal HHF and TIMP-2 level increased in transformed

fibroblast cells. These events are dependent on the nuclear transcription factor activity on

the collagenase promoter in normal HHF cells. On the other hand, in polyoma transform

fibroblast cells these events are not dependent on this collagenase promoter. These results

suggest that oxidative environment induces normal HHF cell proliferation, and the reducing

agent decreases normal HHF cell proliferation by inducing MMP and repressing TIMP gene

transcription. In transformed cells reducing agents inhibit MMP expression and increase

TIMP levels, which suggests a role of antioxidants in preventing tumorigenesis (Au).

Au: Dziadek M; Darling P; Bakker M; Overall M; Zhang RZ; Pan TC; Tillet E; Timpl R;

Chu ML.

Ad: Institute of Reproduction and Development, Monash Medical Centre, Clayton,

Victoria, Australia.

Ti: Deposition of collagen VI in the extracellular matrix during mouse embryogenesis

correlates with expression of the alpha 3(VI) subunit gene.

So: Exp Cell Res; 226(2):302-15, 1996 Aug 1.

Ab: Collagen VI is a microfibrillar component of the extracellular matrix that is predicted

to have an important structural role in matrix organization and a biological function in

mediating cell-matrix interactions. Secreted collagen VI molecules are composed of three

distinct subunits, the alpha 1(VI), alpha 2(VI), and alpha 3(VI) chains. To determine when,

and in which tissues, collagen VI is likely to have a role in embryonic processes, we have

analyzed the expression patterns of the three subunit chains during postimplantation mouse

development by reverse transcriptase-PCR (RT-PCR), in situ hybridization, and

immunofluorescence. No collagen VI protein could be detected in the mouse embryo until

Day 11.5 of gestation, when low levels were localized within the mesoderm layer of the

visceral yolk sac, the subepidermal matrix of branchial arches, and the vessel wall of the

dorsal aorta. Levels of collagen VI mRNA and protein increased during the period from

Days 12.5 to 14.5 in the visceral yolk sac, subepidermal mesenchyme, lung, gut, meninges,

muscle, perichondrium, and vertebral column. The cartilage matrix of ribs and developing

long bones was not stained with collagen VI antisera, but pericellular staining of

chondrocytes was seen in both tissues. Low levels of collagen VI mRNA and protein were

seen in the fetal liver except for the connective tissue of the liver capsule, which was highly

stained. Collagen VI was first detected at significant levels in the developing heart on Day

14.5. These data demonstrate a tissue-specific onset of collagen VI synthesis and deposition

in the extracellular matrix of developing mouse embryos at a much later stage of

development than that reported for fibronectin or collagen I. Sensitive RT-PCR assays

showed that alpha 1(VI) and alpha 2(VI) mRNAs were amplified from extracts of

embryonic tissues as early as Day 7.5, while alpha 3(VI) mRNA was not detected until Day

10.5. Expression of the alpha 3(VI) gene immediately preceded the appearance of

collagen VI protein in embryonic tissues. This correlation is consistent with the proposal

that expression of alpha 3(VI) chains regulates the formation and secretion of collagen VI

trimers and collagen VI matrix deposition during development (Au).

Au: Wiens DJ.

Ad: Department of Biology, University of Northern Iowa, Cedar Falls 50614, USA.

wiens@cobra.uni.edu.

Ti: An alternative model for cell sheet migration on fibronectin during heart formation.

So: J Theor Biol; 179(1):33-9, 1996 Mar 7.

Ab: The emergence of animal form and function depends on cell migrations in the embryo.

Some migrations are accomplished by cells individually, and the mechanism of movement

is predictable by contemporary models of cell adhesion and cytoskeletal function. However,

other migrations occur that involve layers or sheets of cells connected by junctions, and the

mechanism of migration is obscure. An example is the precardiac mesoderm, an

epithelium that migrates anteriorly and ventrally in the early amniote embryo to the position

of heart formation. It moves upon and is influenced by the adjacent endoderm, which has

produced an extracellular matrix. The matrix contains the cell adhesion and cytoskeleton-

activating glycoprotein fibronectin. Some immunolocalization studies have reported that

fibronectin is arrayed in an anterior-to-posterior gradient, and it has been suggested that

directional migration results from a haptotactic response of each cell to the gradient, a

model derived from and supported by experiments with individual cells in culture.

However, we have produced evidence from immunostaining that suggests fibronectin is

arrayed as a localized anterior patch rather than a gradient. We propose an alternative model

for precardiac epithelial migration in which only the anterior cells attach effectively to

fibronectin. Thus adhered, their cytoskeletal contractile activity generates force which

propagates throughout the layer of connected cells, and efficiently pulls them in the proper

direction, following the bending and extending movements of the foregut, notochord and

other structures of the head. Theoretical implications of the two models are discussed (Au).

MATRIZ EXTRACELULAR X CORACAO/MIOCARDIO

Au: Klappacher G; Franzen P; Haab D; Mehrabi M; Binder M; Plesch K; Pacher R; Grimm

M; Pribill I; Eichler HG; et al.

Ad: Department of Cardiology, University of Vienna, Austria.

Ti: Measuring extracellular matrix turnover in the serum of patients with idiopathic or

ischemic dilated cardiomyopathy and impact on diagnosis and prognosis.

So: Am J Cardiol; 75(14):913-8, 1995 May 1.

Ab: Circulating levels of extracellular matrix components were measured by

radioimmunoassays and tested if they were useful for clinical staging in chronic heart

failure. In 41 patients with dilated cardiomyopathy (33 idiopathic and 8 ischemic cases), the

serum concentrations of procollagen type III aminoterminal peptide (PIIINP), type I

collagen telopeptide (ICTP), and basement membrane laminin were significantly higher

than in 30 healthy controls regardless of the underlying etiology. Patients with serum values

of PIIINP, ICTP, and laminin > 7 micrograms/L, 7.6 micrograms/L, and 2.3 U/ml,

respectively, were at higher relative risk for advanced clinical stage, poor hemodynamic

condition, hyponatremia, heart transplantation, and death during follow-up than patients

with low levels, with the exception that serum laminin > 2.3 U/ml was not significantly

associated with hyponatremia and heart transplantation. Despite their interdependence on

liver function, circulating levels of PIIINP and ICTP were independent predictors of

mortality. In 17 of the 41 patients with cardiomyopathy whose explanted hearts were

available for histologic evaluation, serum PIIINP, ICTP, and laminin significantly

correlated with the myocardial area fractions of their tissue analogues (PIIINP vs

myocardial collagen type III, r = 0.784, p = 0.0013; serum ICTP vs myocardial collagen

type I, r = 0.603, p = 0.0527; and serum laminin vs myocardial laminin, r = 0.605, p =

0.0411). In conclusion, the increase in extracellular matrix turnover, which may partially be

derived from fibrosis in the myocardium, can be measured in the serum of patients with

dilated cardiomyopathy, and has an impact on risk stratification and prognosis (Au).

Au: Yamazaki T; Shiojima I; Komuro I; Nagai R; Yazaki Y.

Ad: Department of Medicine III, University of Tokyo School of Medicine, Japan.

Ti: Interaction of cardiac myocytes and non-myocytes in mechanical stress-induced

hypertrophy.

So: Herz; 20(2):109-17, 1995 Apr.

Ab: It is known that mechanical stress directly changes the conformation of the functional

proteins, or directly activates enzymes such as phospholipase in the plasma membrane. The

integrin-cytoskeleton complex may be an alternative candidate structure for a

mechanoreceptor and a transducer. The cytoskeleton has been also shown to play an

important role in secretion. Mechanical stress may stimulate the secretion of some

cytokines or angiotensin II, which may generate multiple intracellular signals as a secondary

event. External stimuli are generally transduced into the nucleus through the activation of

protein kinase cascade. Stretching of cardiac myocytes stimulates the activity of PKC, Raf-

1 kinase, MAP kinase kinase. MAP kinase and S6 kinase. In cardiac myocytes, mechanical

stress directly induces gene expression as well as protein synthesis. Immediate early genes

are first induced, and then fetal-type genes are reinduced. Both in hypertrophied hearts and

in the experimental model of cardiac hypertrophy induced by pressure overload. Ca(2+)-

ATPase content of cardiac myocytes is depressed. Reduced function of sarcoplasmic

reticulum causes insufficient decrease of intracellular calcium in diastole and induces

slowing of ventricular relaxation. In the interstitium of pressure overloaded hearts, the

accumulation of collagen fiber is increased. The abnormal deposit leads to increased

chamber stiffness and diastolic dysfunction. Furthermore, TGF-beta and tissue renin-

angiotensin system are up-regulated in pressure overloaded hearts, both of which accelerate

the interstitial fibrosis (Au).

Au: Andries LJ; Sys SU; Brutsaert DL.

Ad: Department of Physiology, University of Antwerp, Belgium.

Ti: Morphoregulatory interactions of endocardial endothelium and extracellular material in

the heart.

So: Herz; 20(2):135-45, 1995 Apr.

Ab: The endocardium forms the inner lining of the cavities of the heart. The luminal surface

of the cardiac wall is subjected to considerable cyclical physico-chemical forces. These

forces can have structural and physiological consequences both for the endocardial

endothelium and for the subjacent interstitial tissue. In the latter tissue space, the

extracellular matrix (ECM) plays a dominant role during cardiogenesis. For example, this

role becomes evident from the influence of fibronectin in the directional migration of

proendocardial cells and in the formation of a trabeculated heart. In particular, the complex

processes occurring in the valves of the developing heart illustrate a spatiotemporally

regulated expression of ECM components and adhesion molecules. In the adult heart, the

endocardial interstitial tissue consists of a thin basal lamina, a reticular lamina and a

fibroelastic layer which contains some fibroblasts, smooth muscle cells and a heterogeneous

population of nerve fibers. Unlike in arteries, elastic fiber in the fibroelastic layer of

ventricular endocardium do not constitute an elastic lamina. Differences in thickness of the

endocardium between atria and ventricles, as well as the diffuse and focal endocardial

fibrosis during ageing have been related to mechanical stress and local turbulence of flow.

Although endocardial fibrosis is a common pathological finding in various

cardiomyopathies, our knowledge on the structural organization and on the pathogenetic

role of ECM is very limited, mainly by the lack of suitable experimental models (Au).

Au: Maisch B.

Ti: Extracellular matrix and cardiac interstitium: restriction is not a restricted phenomenon

[editorial].

So: Herz; 20(2):75-80, 1995 Apr.

Au: Weber KT; Sun Y; Katwa LC.

Ad: Department of Internal Medicine, University of Missouri Health Sciences Center,

Columbia, USA.

Ti: Local regulation of extracellular matrix structure.

So: Herz; 20(2):81-8, 1995 Apr.

Ab: The extracellular matrix (ECM) is composed of various collagens, glycosaminoglycans,

and elastin bathed by a tissue fluid found throughout the interstitial space. It is this

substratum in which fibroblasts and macrophages normally reside, where fibroblast

phenotypic transformation occurs, and into which inflammatory cells migrate when called

upon during tissue repair. Many diseases, expressed in an organ-specific manner, require

organ-specific ECM remodeling. Regulation of fibrillary type I collagen synthesis, whose

disproportionate (relative to degradation) accumulation is characteristic of the tissue

fibrosis that adversely alters organ function, is therefore of considerable importance.

Emerging evidence implicates angiotensin converting enzyme (ACE), found in fibroblast-

like cells, and ACE-related peptides, angiotensin II and bradykinin, in serving important

regulatory functions that influence wound healing and thereby ECM structure in health and

disease. The heart and its collagen matrix have been targeted for discussion in this brief

review (Au).

Au: Mollnau H; M�nkel B; Schaper J.

Ad: Max-Planck-Institute for Physiological and Clinical Research, Department of

Experimental Cardiology, Bad Nauheim, Germany.

Ti: Collagen VI in the extracellular matrix of normal and failing human myocardium.

So: Herz; 20(2):89-94, 1995 Apr.

Ab: Our own previous studies of the composition of the extracellular matrix of human

failing hearts showed that collagen VI seems to play a major role in the origin of cardiac

fibrosis. Therefore, collagen VI was investigated in more detail in tissue samples taken

from clinically normal left ventricle and from myocardium failing because of dilated

cardiomyopathy. Tissue sections prepared with collagen VI antibodies were examined by

fluorescence microscopy using conventional or confocal laser scanning microscopy. In

normal myocardium, collagen VI was located in both, endomysium and perimysium, in

blood vessels it surrounded closely individual myocytes. Failing myocardium showed

enlargement of the extracellular space and collagen VI was abundant. The localisation was

perivascular as well as interstitial in fine or thick bundles enclosing the myocytes

completely. In hearts with far progressed failure areas of replacement fibrosis containing

increased amounts of collagen VI were evident. Double-staining for vimentin and collagen

VI revealed a close interaction with fibroblasts. Although the function of collagen VI is not

yet entirely clear it seems obvious that collagen VI plays an important role in the

development of fibrosis in the failing heart (Au).

Au: Wilke A; Sch”nian U; Herzum M; Hengstenberg C; Hufnagel G; Brilla CG; Maisch B.

Ad: Abteilung Kardiologie, Philipps-Universit„t Marburg.

Ti: Extrazellul„re Matrix und Zytoskelett des Myokards bei kardialer

Entz�ndungsreaktion. / The extracellular matrix and cytoskeleton of the myocardium in

cardiac inflammatory reaction.

So: Herz; 20(2):95-108, 1995 Apr.

Ab: The cardiac cytoskeleton and the extracellular matrix play an essential role for

maintaining cellular integrity and function of the myocardium. The network of microtubules

and intermediate filaments are disrupted by the inflammatory reaction which depends on

resident cells (myocytes, fibroblasts, endothel cells) and on systemic cells (granulocytes,

macrophages, monocytes, lymphocytes). Changes in the cardiac cytoskeleton and the

extracellular matrix may affect contractile function, since the cytoskeleton organizes the

intra- and intercellular architecture. The inflammation in heart disease and the induction of

fibrosis are mediated by cytokines and growth factors derived from fibroblast activation and

from the B- and T-cell activity. A possible connecting link for the induction of fibrosis is

the presentation of the myocardial antigens to the immune system and its subsequent

cellular and humoral autoreactive response (Figure 1). Different autoantibodies to

sarcolemmal and myolemmal antigens, to laminin, to extracellular matrix proteins, to the

collagens and to myofibrils were demonstrated both in endomyocardial biopsy and as

circulating autoantibodies in the peripheral blood. The pathophysiological role of the

cytoskeleton and the extracellular matrix are well defined for beta-tubulin, fibronectin,

laminin, desmin, vimentin, vinculin and collagen: beta-tubulin is increased or altered in

dilated cardiomyopathy (DCM). Fibronectin appears in irregular forms in DCM as well.

Ultrastructural analysis showed an increased content of laminin in basement membranes. In

addition anti-laminin antibodies were found in 73% of patients with myocarditis and in

78% of patients with DCM. Desmin (z-bands) are partly destroyed in DCM. Anti-desmin

antibody titers as indicators of a possible secondary immune response are found high in

patients with acute myocarditis declining during reconvalescence and are also elevated in

DCM. The vimentin of the endothelial cells and the vinculin of the sarcolemmal membrane

and the intercalated discs have been demonstrated to be irregularly shaped and increased in

content in DCM whereas in myocarditis their appearance and content is still unknown. The

intracellular content of collagen type 5 is increased in DCM and in myocarditis. The

presence of autoantibodies to components of the cytoskeleton and the extracellular matrix

in myocarditis and perimyocarditis is well-described. Antibodies to the myolemma and the

sarcolemma are found in almost all patients with perimyocarditis in the serum or bound in

the biopsy. Some of them have been known cytolytic in vitro to isolated heart cells. In

pericarditis a shift to antibodies to the extracellular matrix, collagen and intermediate

filaments is observed among the circulating antibodies.(ABSTRACT TRUNCATED AT

400 WORDS) (Au).

Au: K lm n F; Vir gh S; M¢dis L.

Ad: Department of Pathology, Postgraduate Medical University, Budapest, Hungary.

Ti: Cell surface glycoconjugates and the extracellular matrix of the developing mouse

embryo epicardium.

So: Anat Embryol (Berl); 191(5):451-64, 1995 May.

Ab: Cell surface glycoconjugates and the extracellular matrix (ECM) of the proepicardium

and the developing epicardium were studied in early mouse embryos by light and electron

microscopy with histochaemical and immunocytochaemical techniques. The extracardially

located proepicardium consists of polarized mesothelial cells forming the proepicardial

vesicles. These vesicles contain a fine proteoglycan network and an acellular ECM rich in

hyaluronic acid. Membrane-bound glycoconjugates are shown with cuprolinic blue, alcian

blue and ruthenium red on the apical (outer) cell surface, while fibronectin and laminin are

present on the basal (luminal) cell surface. These membrane and matrix components of the

proepicardium might be involved in specific attachment of proepicardial cells to the bare

heart tube and might facilitate the initial migration of epicardial cells over the myocardial

surface. In the cell coat of the cardiomyocytes of the bare heart tube the fibronectin and

laminin are concentrated in patches. The formation of the epicardial covering is a rapid

process, requiring only about 2 days (9-11 days) to ensheath the entire heart tube from the

inflow to the outflow segment. The subepicardial matrix between the newly formed

epicardial covering and myocardial layer is acellular at first, but contains a condensing

proteoglycan network, membrane and matrix fibronectin, type IV collagen and laminin on

the myocardial cell surface. The formation and the distribution of the subepicardial ECM

show regional characteristics. The accumulating ECM forms wide subepicardial spaces and

protuberances in the atrioventricular and interventricular sulci. The sulci of the heart seem

to provide the optimum microenvironment for haematopoiesis and vasculogenesis.

Haematopoietic islands and coronary vessel forerunners appear and concentrate in the

regularly spaced surface protuberances. The vasculogenesis proceeds from the inflow to the

outflow segment of the heart. The first blood capillaries appear in the sinoatrial sulcus of

the 10-day embryo. By 11-13 days the subepicardial blood vessels form an interconnected

network and establish the coronary artery orifices (Au).

Au: Dollery CM; McEwan JR; Henney AM.

Ad: Division of Cardiology, University College London (UK) Medical School.

Ti: Matrix metalloproteinases and cardiovascular disease.

So: Circ Res; 77(5):863-8, 1995 Nov.

Au: Nagasawa K; Zimmermann R; M�nkel B; Linz W; Sch”lkens B; Schaper J.

Ad: Max-Planck-Institute, Bad Nauheim, Germany.

Ti: Extracellular matrix deposition in hypertensive hearts antifibrotic effects of ramipril.

So: Eur Heart J; 16 Suppl C:33-7, 1995 May.

Ab: Hypertension induced in rats by suprarenal banding has a blood pressure elevating

effect that is accompanied by the occurrence of cardiac hypertrophy and fibrosis. This

phenomenon is already present at 2 weeks after banding and persists up to 1.5 years. The

increase in cardiac weight is mostly due to the development of fibrosis, since myocytes are

only slightly increased in size. The fibrotic tissue consists mainly of fibronectin and

collagen and contains numerous cellular elements. The occurrence of fibrosis can be

completely inhibited by the administration of the specific ACE inhibiting drug, ramipril,

which indicated that angiotensin II may directly stimulate fibroblasts to produce fibronectin

and collagen. The antifibrotic effect of ramipril was also present in a low dosage that did

not lower blood pressure, confirming the hypothesis that angiotensin II has a direct effect

on connective tissue cells and their ability to produce extracellular matrix proteins. The

direct effect of the renin-angiotensin system on the activity of interstitial cells was further

proven by molecular biology techniques showing an upregulation of transcription for

collagen I and III which is prevented by ACE inhibition (Au).

Au: Little CD; Rongish BJ.

Ad: Department of Cell Biology, Medical University of South Carolina, Charleston 29425-

2204, USA.

Ti: The extracellular matrix during heart development.

So: Experientia; 51(9-10):873-82, 1995 Sep 29.

Ab: The embryonic extracellular matrix, which is comprised of glycosaminoglycans,

glycoproteins, collagens, and proteoglycans, is believed to play multiple roles during heart

morphogenesis. Some of these ECM components appear throughout development,

however, certain molecules exhibit an interesting transient spatial and temporal distribution.

Due to significant new data that have been gathered predominantly in the past 10 years, a

comprehensive review of the literature is needed. The intent of this review is to highlight

work that addresses mechanisms by which extracellular matrix influences vertebrate heart

development (Au).

MATRIZ EXTRACELULAR X CORACAO/MIOCARDIO

Au: Lonn E; Factor SM; Van Hoeven KH; Wen WH; Zhao M; Dawood F; Liu P.

Ad: Centre for Cardiovascular Research, University of Toronto, Ontario.

Ti: Effects of oxygen free radicals and scavengers on the cardiac extracellular collagen

matrix during ischemia-reperfusion.

So: Can J Cardiol; 10(2):203-13, 1994 Mar.

Ab: OBJECTIVE: Collagen is lysed early during ischemia-reperfusion, but whether this is

due to ischemia or reperfusion injury is not known. The effect of oxygen free radicals and

free radical scavengers on left ventricular hemodynamics, myocardial morphology and

collagen content were studied in an isolated, Langendorff-perfused rat heart model of

regional ischemia-reperfusion. METHODS: All hearts received left anterior descending

coronary artery ischemia for 20 mins. Group 1 had ischemia only; group 2 had ischemia

followed by reperfusion with oxygenated Krebs-Henseleit buffer for 20 mins; group 3 had

oxygen free radicals generated by hypoxanthine and xanthine oxidase during reperfusion;

group 4 had free radical scavengers with superoxide dismutase plus catalase; group 5 had

both oxygen free radicals and free radical scavengers during reperfusion. RESULTS: Left

ventricular developed pressure decreased significantly in group 3 during ischemia followed

by reperfusion (58 +/- 3.1 mmHg versus 42 +/- 2.4 mmHg, P = 0.004), but did not change

significantly in any of the other groups. Necrosis score on pathology was highest in group 3;

this score also was higher than that in group 5 with free radical scavengers added (3.0 +/-

0.3 versus 2.0 +/- 0.4, P = 0.07) and higher than that of group 2 with reperfusion with buffer

only (3.0 +/- 0.3 versus 1.4 +/- 0.5, P < 0.05). Collagen content decreased significantly

compared with control in group 3 only with ischemia followed by reperfusion with the

addition of oxygen free radicals (18.4 +/- 1.5 versus 11.9 +/- 1.7 g/mg protein, P < 0.05).

The addition of free radical scavengers in group 5 mainly attenuated the collagen loss.

Scanning electron microscopy revealed profound structural changes of the extracellular

collagen matrix in numerous regions of 'stunning' independent of tissue necrosis.

CONCLUSIONS: We conclude that: first, oxygen free radicals trigger significant collagen

damage and left ventricular dysfunction during reperfusion; second, these changes extend

beyond the ischemic damage alone; and third, free radical scavengers can effectively limit

oxygen free radical-induced collagen loss and left ventricular dysfunction (Au).

Au: MacKenna DA; Omens JH; McCulloch AD; Covell JW.

Ad: Department of Medicine (Cardiology), University of California, San Diego, La Jolla

92093.

Ti: Contribution of collagen matrix to passive left ventricular mechanics in isolated rat

hearts.

So: Am J Physiol; 266(3 Pt 2):H1007-18, 1994 Mar.

Ab: Although it makes up only 2-6% of left ventricular dry weight, collagen is thought to

be the major structural protein determining passive ventricular stiffness. However, the

relationship between structure of the extracellular matrix and passive mechanics is not

understood. Hence, to deplete the collagen matrix, 16 rat hearts were perfused with

bacterial collagenase for 60 min. Quantitative morphology using picrosirius red revealed

a 36% decrease in collagen area fraction predominantly in the medium-sized fibers.

Scanning electron microscopy revealed damage to the endomysial struts. Passive pressure-

volume curves showed increases in left ventricular volume at all pressures (from 0.203 +/-

0.061 to 0.265 +/- 0.061 ml at 5 mmHg, P < 0.0001). Strain during loading, calculated from

lengths obtained from a triplet of piezoelectric crystals, was unchanged with collagen

depletion. However, remodeling strain computed from the collagenase-treated state referred

to the Krebs solution-treated state at the same ventricular pressure showed both

circumferential (0.145 +/- 0.166 to 0.170 +/- 0.158) and longitudinal (0.070 +/- 0.120 to

0.068 +/- 0.069) stretching. Sarcomere lengths increased at all depths (5.2% at midwall).

Thus alterations in the extracellular matrix lead to increased ventricular volume and

sarcomere lengths without altering ventricular compliance (Au).

Au: Weber KT; Sun Y; Tyagi SC; Cleutjens JP.

Ad: Department of Internal Medicine, University of Missouri Health Sciences Center,

Columbia 65212.

Ti: Collagen network of the myocardium: function, structural remodeling and regulatory

mechanisms.

So: J Mol Cell Cardiol; 26(3):279-92, 1994 Mar.

Ab: A collagen network, composed largely of type I and III fibrillar collagens, is found in

the extracellular space of the myocardium. This network has multiple functions which

includes a preservation of tissue architecture and chamber geometry. Given its tensile

strength, collagen is a major determinant of tissue stiffness. Its disproportionate

accumulation, in the form of either a reactive or a reparative fibrosis, further increases

stiffness. A degradation of collagen tethers, on the other hand, is an anatomic requisite for a

distortion in tissue architecture and a reduction in stiffness that can lead to chamber

dilatation, wall thinning, and even rupture of the myocardium. Collagen turnover in the

myocardium is dynamic. When synthesis exceeds degradation, an adverse accumulation of

collagen appears to distort tissue structure. This is true for either the hypertrophied and/or

nonhypertrophied ventricle. Factors that contribute to the appearance of myocardial fibrosis

are largely different from those that promote cardiac myocyte growth. Included amongst

these fibrogenic factors are effector hormones of the reinin-angiotensin-aldosterone system

(RAAS). Studies conducted both in intact animals (relative to dietary sodium intake) and in

cultured adult cardiac fibroblasts have pointed toward the association between collagen

accumulation and chronic elevations in circulating angiotensin II and aldosterone. A tissue

hormonal system involving angiotensin II, endothelins and bradykinin, may likewise

regulate fibrogenesis. In this regard, angiotensin converting enzyme is found in connective

tissue of the normal heart, including the matrix of heart valves and the adventitia of the

intramural coronary arteries, and fibrous tissue that forms following infarction or with

chronic RAAS activation. The importance of ACE in the regulation of local angiotensin II

and bradykinin levels and their contribution to collagen turnover is a fruitful area of

research with important clinical implications. The myocardium also contains a proteolytic

system, including collagenase. The characteristics and regulation of matrix

metalloproteinases and their tissue inhibitors in various cardiovascular disease states

requires further investigation (Au).

Au: Courtman DW; Pereira CA; Kashef V; McComb D; Lee JM; Wilson GJ.

Ad: Centre for Biomaterials, University of Toronto, Ontario, Canada.

Ti: Development of a pericardial acellular matrix biomaterial: biochemical and mechanical

effects of cell extraction.

So: J Biomed Mater Res; 28(6):655-66, 1994 Jun.

Ab: There is evidence to suggest that the cellular components of homografts and

bioprosthetic xenografts may contribute to calcification or immunogenic reactions. A four-

step detergent and enzymatic extraction process has been developed to remove cellular

components from bovine pericardial tissue. The process results in an acellular matrix

material consisting primarily of elastin, insoluble collagen, and tightly bound

glycosaminoglycans. Light and electron microscopy confirmed that nearly all cellular

constituents are removed without ultrastructural evidence of damage to fibrous components.

Collagen denaturation temperatures remained unaltered. Biochemical analysis confirmed

the retention of collagen and elastin and some differential extraction of

glycosaminoglycans. Low strain rate fracture testing and high strain rate viscoelastic

characterization showed that, with the exception of slightly increased stress relaxation, the

mechanical properties of the fresh tissue were preserved in the pericardial acellular

matrix. Crosslinking of the material in glutaraldehyde or poly(glycidyl ether) produced

mechanical changes consistent with the same treatments of fresh tissue. The pericardial

acellular matrix is a promising approach to the production of biomaterials for heart valve or

cardiovascular patching applications (Au).

Au: Simpson DG; Terracio L; Terracio M; Price RL; Turner DC; Borg TK.

Ad: Department of Developmental Biology and Anatomy, University of South Carolina

Medical School, Columbia 29208.

Ti: Modulation of cardiac myocyte phenotype in vitro by the composition and orientation of

the extracellular matrix.

So: J Cell Physiol; 161(1):89-105, 1994 Oct.

Ab: Cellular phenotype is the result of a dynamic interaction between a cell's intrinsic

genetic program and the morphogenetic signals that serve to modulate the extent to which

that program is expressed. In the present study we have examined how morphogenetic

information might be stored in the extracellular matrix (ECM) and communicated to the

neonatal heart cell (NHC) by the cardiac alpha 1 beta 1 integrin molecule. A thin film of

type I collagen (T1C) was prepared with a defined orientation. This was achieved by

applying T1C to the peripheral edge of a 100 mm culture dish. The T1C was then drawn

across the surface of the dish in a continuous stroke with a sterile cell scraper and allowed

to polymerize. When NHCs were cultured on this substrate, they spread, as a population,

along a common axis in parallel with the gel lattice and expressed an in vivo-like

phenotype. Individual NHCs displayed an elongated, rod-like shape and disclosed

parallel arrays of myofibrils. These phenotypic characteristics were maintained for at least 4

weeks in primary culture. The evolution of this tissue-like organizational pattern was

dependent upon specific interactions between the NHCs and the collagen-based matrix that

were mediated by the cardiac alpha 1 beta 1 integrin complex. This conclusion was

supported by a variety of experimental results. Altering the tertiary structure of the matrix

or blocking the extracellular domains of either the cardiac alpha 1 or beta 1 integrin chain

inhibited the expression of the tissue-like pattern of organization. Neither cell-to-cell

contact or contractile function were necessary to induce the formation of the rod-like cell

shape. However, beating activity was necessary for the assembly of a well-differentiated

myofibrillar apparatus. These data suggest that the cardiac alpha 1 beta 1 integrin complex

serves to detect and transduce phenotypic information stored within the tertiary structure of

the surrounding matrix (Au).

Au: Swan HJ.

Ad: Division of Cardiology, Cedars-Sinai Medical Center, Los Angeles, California.

Ti: Left ventricular dysfunction in ischemic heart disease: fundamental importance of the

fibrous matrix.

So: Cardiovasc Drugs Ther; 8 Suppl 2:305-12, 1994 May.

Ab: The contractile function of the myocardium is coordinated by a fibrous matrix of

exquisite organization and complexity. In the normal heart, and apparently in physiological

hypertrophy, this matrix is submicroscopic. In pathological states changes are frequent, and

usually progressive. Thickening of the many elements of the fine structure is due to an

increased synthesis of Type I collagen, This change, which affects the myocardium in a

global manner, can be observed by light microscopy using special techniques. Perivascular

fibrosis, with an increase in vascular smooth muscle, is accompanied by development of

fibrous septa, with a decrease in diastolic compliance. These structural changes are believed

to be due to increased activation of the renin-angiotensin-aldosterone system, and to be

independent of the processes of myocyte hypertrophy. Reparative or replacement fibrosis is

a separate process by means of which small and large areas of necrosis heal, with the

development of coarse collagen structures, which lack a specific organizational pattern.

Regarding ischemic heart disease, an increase in tissue collagenase is found in experimental

myocardial ®stunning® and in the very early phase of acute infarction. Absence of

elements of the fibrous matrix allow for myocyte slippage, and--if the affected area is large-

-cardiac dilatation. If, subsequently, the necrosis becomes transmural, there is further

disturbance of collagen due to both mechanical strain and continued autolysis, During

healing collagen synthesis increases greatly to allow for reparative scarring in the available

tissue matrix. In cases of infarction with moderate or severe initial dilatation, pathological

hypertrophy of the spared myocardium is progressive, accounting for late heart failure and

poor survival.(ABSTRACT TRUNCATED AT 250 WORDS) (Au).

Au: Hurle JM; Kitten GT; Sakai LY; Volpin D; Solursh M.

Ad: Department of Biological Sciences, University of Iowa, Iowa City 52242.

Ti: Elastic extracellular matrix of the embryonic chick heart: an immunohistological study

using laser confocal microscopy.

So: Dev Dyn; 200(4):321-32, 1994 Aug.

Ab: The ®elastic matrix® constitutes a specialized component of the extracellular matrix

which confers resiliency to tissues and organs subjected to repeated deformations. The role

of the elastic matrix in living organisms appears to be of key importance since diseases

characterized by expression of defective inherited genes which encode components of the

elastic matrix lead to premature death. While the elastic matrix of adult organs has received

a great deal of attention, little is known about when it first appears in embryonic tissues or

its possible role in developing organs. In the present study we have performed an

immunohistochemical study of the distribution of elastin and three additional components

often associated with elastic matrices in adult tissues (i.e., fibrillin, emilin, and type VI

collagen) during the development of the chicken embryonic heart. The three-dimensional

arrangement of these components was established through the observation of whole-amount

specimens with scanning laser confocal microscopy. Our results revealed three different

periods of heart development regarding the composition of the elastic matrix. Prior to stage

21 the embryonic heart lacks elastin but exhibits a matrix scaffold of fibrillin and emilin

associated with the endocardium and the developing cardiac jelly. Between stages 22 and

29 the heart shows a transient elastic scaffold in the outflow tract which contains elastin,

fibrillin, and emilin. Elastin-positive fibrillar material is also observed during these stages

in the base of the atrioventricular cushion adjacent to the myocardial wall. In addition,

emilin-positive material appears to be associated with the zones of formation of ventricular

trabeculae. Collagen type VI was not detected during these early stages. From stage 30 to

stage 40 a progressive modification of the pattern of distribution of elastin, fibrillin, emilin,

and collagen type VI is observed in association with the formation of the definitive four-

chambered heart. The distribution of the elastic scaffold in the outflow tract appears to be

rearranged and becomes restricted to the roots of the main arteries. Each of the components

studied here is also deposited at increasing levels in the developing valvular apparatus

including the valve leaflets and the chordae tendinea. The components are also present in

the subendocardial space where they form aligned fibrillar tracts, an arrangement suggestive

of a role in ventricular contractile function. The epicardium constitutes an additional region

of elastic matrix deposition during these later stages and contains elastic, fibrillin, and

collagen type VI.(ABSTRACT TRUNCATED AT 400 WORDS) (Au).

Au: Sanchez-Quintana D; Climent V; Garcia-Martinez V; Macias D; Hurle JM.

Ad: Departamento de Ciencias Morfol¢gicas, Facultad de Medicina, Universidad de

Extremadura, Badajoz, Spain.

Ti: Extracellular matrix arrangement in the papillary muscles of the adult rat heart.

Alterations after doxorubicin administration and experimental hypertension.

So: Basic Res Cardiol; 89(4):279-92, 1994 Jul-Aug.

Ab: In the present study, we analyzed the components of the extracellular matrix (ECM)

and its arrangement at the level of the papillary muscles in the adult rat heart using light and

transmission and scanning electron microscopy techniques. Our results reveal that after a

single dose (6 mg/kg) of dexorubicin to cause a significant decrease and disorganization of

the endomysium and perimysium in the first week after injection, affecting the endomysial

struts and perimysial strands. Degenerating myocytes and alterations of the coiled

perimysial fibers were characteristic 4 weeks after treatment. After 8 weeks,

ultrastructural alterations at the level of the plasma membrane of the myocytes and adjacent

collagen network were present in the tip of the papillary muscles. These alterations may

be responsible for the inefficiency of the valvular apparatus as an initial factor implicated in

doxorubicin-induced congestive heart failure. Experimental hypertension, produced by

constriction of the abdominal aorta, induced hypertrophy of the left ventricle, with

increased perimysium and endomysium of the ECM at the level of the papillary muscles 4

weeks after aortic banding. Interstitial and perivascular fibrosis were observed 8 weeks

after surgical treatment, and macrophages around the degenerating myocytes were

characteristic 16 weeks after treatment. These alterations of the ECM network have been

correlated with their possible implication in ventricular biomechanical properties (Au).

Au: Omura T; Kim S; Takeuchi K; Iwao H; Takeda T.

Ad: First Department of Internal Medicine, Osaka City University Medical School, Japan.

Ti: Transforming growth factor beta 1 and extracellular matrix gene expression in

isoprenaline induced cardiac hypertrophy: effects of inhibition of the renin-angiotensin

system.

So: Cardiovasc Res; 28(12):1835-42, 1994 Dec.

Ab: OBJECTIVE: The aim was to investigate changes in cardiac transforming growth

factor beta 1 (TGF-beta 1), fibronectin, and collagen types I and III mRNA levels in

isoprenaline induced cardiac hypertrophy, and the effects of delapril, an angiotensin

converting enzyme inhibitor, and TCV-116, an angiotensin II type 1 receptor antagonist, on

this hypertrophy. METHODS: Rats were continuously infused with saline and low or high

dose of isoprenaline (0.5 or 3 mg.kg-1.d-1) by an osmotic minipump for 24 h, 48 h or 7

d. Treatment with delapril (100 mg.kg-1.d-1) or TCV-116 (10 mg.kg-1.d-1) was started

from 1 d before the implantation of minipump to the end of experiments. After the

experimental periods, left ventricular weight was measured and the mRNA was extracted

and measured by northern blot hybridisation. RESULTS: Both low and high doses of

isoprenaline infusion resulted in increased left ventricular weight. With low dose

infusion, cardiac TGF-beta 1 mRNA was not stimulated throughout the infusion, while

fibronectin mRNA and collagen types I and III mRNAs began to increase at 24 h and 48 h,

respectively, after the infusion. In high dose isoprenaline infusion, not only was

extracellular matrix mRNA but also TGF-beta 1 mRNA in the ventricle significantly

increased. TCV-116 prevented isoprenaline induced left ventricular hypertrophy as much as

delapril. However, with delapril or TCV-116, the time course of TGF-beta 1 and ECM

mRNA expression was almost similar to isoprenaline infusion only. CONCLUSIONS:

The extracellular matrix mRNA expressions are enhanced in myocardial hypertrophy by a

low dose of isoprenaline, which is probably not mediated by TGF-beta 1. The preventive

effects of TCV-116 on this hypertrophy indicate that the inhibitory effects of angiotensin

converting enzyme inhibitor on cardiac hypertrophy are due to the inhibition of angiotensin

II and that angiotensin II type I receptor plays an important role in isoprenaline induced left

ventricular hypertrophy. However, the renin-angiotensin system may play a minor role in

isoprenaline induced cardiac fibrosis (Au).

Au: de Sousa M.

Ad: Abel Salazar Institute for the Biomedical Sciences, Oporto, Portugal.

Ti: Lymphocyte traffic and positioning in vivo: an expanded role for the ECM, the VLA

proteins and the cytokines.

So: Pathol Res Pract; 190(9-10):840-50, 1994 Oct.

Ab: The continuous circulation of lymphocytes between blood and lymph, constitutes, with

the specific recognition of foreign antigens and with memory, one of the hallmarks of the

immunological system. In the routine process of recirculating between blood and lymph in

adult life, lymphocytes display the unique capacity of recognizing ®self within self®. The

physiological recognition of ®self within self® is expressed at three levels: (1) an overall

ability to distinguish between peripheral lymphoid and non-lymphoid organs, (2) the ability

of lymphocyte subpopulations to discriminate between peripheral lymphoid organs, (3) a

fine recognition of distinct microenvironments within the peripheral lymphoid organs.

Historically, interest in regulation of entry into the lymph dominated this field, focusing

primarily on the interaction of lymphocytes with post-capillary venules with high

endothelium found in some higher vertebrate lymph nodes. Lymphocytes, however, enter

the lymph in species without lymph nodes, and lymphocytes recirculation is well

established in fetal life. Regardless of route of entry, lymphocytes in birds, fish, rodents,

and humans enter the peripheral lymphoid organs and display the capacity to segregate and

arrange themselves in distinct territories, a phenomenon called ®ecotaxis®. This paper

reviews the evidence for the relative contribution of so called specialized lymphocyte

endothelium interactions and other interactions, to the physiological regulation of

lymphocyte traffic and positioning. Of the latter, interactions of lymphocytes with the ECM

appear of some significance for two reasons: there is a selective distribution of some

ECM components in peripheral lymphoid organ areas, as recently shown for tenascin in the

thymus-dependent zones (Chilosi et al., Am J Pathol 143: 1348-1355, 1993). This selective

distribution may serve as a basis for preferential T cell migration through those zones. The

abnormal expression of tenascin in non-lymphoid organs with autoimmune lesions may

serve as an identical basis for abnormal T lymphocyte migration in autoimmunity

(Chilosi, personal communication). Additional evidence for abnormal cell-ECM

interactions playing a role in autoimmune-like lesions comes from the recent observations

in TGF-beta 1 knockout mice, in which mononuclear cell infiltration of the heart and lungs

has been corrected by the systemic administration of synthetic FN peptides (Hines at al.,

PNAS 91:5187-5191, 1994). Changes in expression of ECM components have aso being

described in rat heart allografts preceding lymphocyte accumulation in the process of

allograft rejection (Coito et atl. Transplantation 57:599-605, 1994).(ABSTRACT

TRUNCATED AT 400 WORDS) (Au).

Au: Andrade ZA.

Ad: Centro de Pesquisas Gon‡alo Moniz (FIOCRUZ), Salvador, BA, Brasil.

Ti: Extracellular matrix degradation in parasitic diseases.

So: Braz J Med Biol Res; 27(9):2273-81, 1994 Sep.

Ab: 1. Fibrosis is an important manifestation of several parasitic diseases, but is not

irreversible. A marked degree of extracellular matrix degradation can occur after cure of

parasitism. Patients with the hepatosplenic form of schistosomiasis undergo considerable

resorption of portal fibrosis months or years after curative treatment as demonstrated by

ultrasonography and pathological examination. 2. Studies of the post-treatment degradation

of extracellular matrix in schistosomal periovular granulomas have demonstrated two forms

of collagen degradation: in hepatic granulomas formed during early infection a rapid

process occurs, with the extracellular breakdown of fibers and internalization of collagen

fragments, whereas during late infection, degradation is slow and is accompanied by

focal electrondense and/or lytic changes. 3. Extensive extracellular matrix degradation and

resorption occurring after curative treatment was recently described in the liver of a man

with advanced visceral leishmaniasis and in the heart of mice with chronic Chagas' disease

(Au).

Au: Murdoch AD; Liu B; Schwarting R; Tuan RS; Iozzo RV.

Ad: Department of Pathology and Cell Biology, Thomas Jefferson University, Philadelphia

19107.

Ti: Widespread expression of perlecan proteoglycan in basement membranes and

extracellular matrices of human tissues as detected by a novel monoclonal antibody against

domain III and by in situ hybridization.

So: J Histochem Cytochem; 42(2):239-49, 1994 Feb.

Ab: Perlecan, a multidomain heparan sulfate proteoglycan (PG), is an intrinsic component

of basement membranes and extracellular matrices. We used a prokaryotic expression

vector to generate fusion proteins encoding various domains of human perlecan protein core

and these recombinant proteins were used as immunogens to produce mouse anti-human

monoclonal antibodies (MAb). One MAb, designated 7B5, was characterized by Western

blotting and ELISA and was shown to react specifically with the laminin-like region of

perlecan (Domain III) but not with two other fusion proteins encoding Domain II or V.

This perlecan epitope was detected by immunoenzymatic staining in the basement

membranes of human tissues including pituitary gland, skin, breast, thymus, prostate, colon,

liver, pancreas, spleen, heart, and lung. All vascular basement membranes tested contained

this gene product. In addition, sinusoidal vessels of liver, spleen, lymph nodes, and pituitary

gland expressed high levels of perlecan in the subendothelial region. In situ hybridization,

using as probe the same human cDNA-encoding Domain III, localized perlecan mRNA to

specific cell types within the tissues and demonstrated that in skin, perlecan appears to be

synthesized exclusively by connective tissue cells in the dermal layer. The availability of

MAb against precise regions of human perlecan will allow the investigation of this gene

product in normal and diseased states (Au).

MATRIZ EXTRACELULAR X CORACAO/MIOCARDIO

Au: Roman J; McDonald JA.

Ad: Department of Medicine (111), Atlanta Veterans Affairs Medical Center, Emory

University School of Medicine, GA 30033.

Ti: Fibulin's organization into the extracellular matrix of fetal lung fibroblasts is dependent

on fibronectin matrix assembly.

So: Am J Respir Cell Mol Biol; 8(5):538-45, 1993 May.

Ab: Fibulin is a newly described extracellular matrix (ECM) glycoprotein whose function

has not been elucidated. We have observed that cultured fetal lung fibroblasts produce

fibulin and have postulated that its expression may be important during lung development.

To begin to understand the potential function of fibulin in lung development, we examined

its expression and distribution in cultured fetal lung fibroblasts. Immunofluorescence

staining of cultured fibroblasts revealed that fibulin was distributed upon their surface in a

fibrillar array resembling fibronectin (FN), another ECM glycoprotein expressed by fetal

lung fibroblasts and implicated in lung and heart development. Detection of fibulin by

immunofluorescence staining of nonpermeabilized cells, its immunoprecipitation from

125I-cell surface-labeled fibroblasts, pulse-chase analysis, and temperature-induced phase

separation studies revealed that fibulin is an ECM peripheral membrane protein that is

synthesized and secreted by cultured fetal lung fibroblasts shortly after plating and

incorporated into their matrix in a divalent cation-dependent manner. Because fibulin co-

distributes with both FN and the FN receptor, the integrin alpha 5 beta 1, we examined the

possibility that fibulin was interacting with both components. Dissociation of FN receptors

from FN fibers with anti-FN receptor antibodies did not affect fibulin's distribution,

suggesting that fibulin binds FN and that this interaction is not affected by the state of FN

receptor binding. Finally, inhibition of FN matrix assembly prevented the deposition of

fibulin, providing further support for FN-fibulin interactions and suggesting that fibulin

deposition is dependent on FN matrix assembly (Au).

Au: Brilla CG; Maisch B; Weber KT.

Ad: Innere Medizin, SP Kardiologie, Philipps-Universit„t Marburg.

Ti: Renin-angiotensin system and myocardial collagen matrix remodeling in hypertensive

heart disease: in vivo and in vitro studies on collagen matrix regulation.

So: Clin Investig; 71(5 Suppl):S35-41, 1993.

Ab: The interstitial space of the myocardium is composed of nonmyocyte cells and a highly

organized collagen network which serves to maintain the architecture and mechanical

behavior of the myocardial walls. It is the myocardial collagen matrix that determines

myocardial stiffness in the normal and structurally remodeled myocardium. In hypertensive

heart disease, the heterogeneity in myocardial structure, created by the altered behavior of

nonmyocyte cells, particularly cardiac fibroblasts which are responsible for collagen

synthesis and degradation, explains the appearance of diastolic and/or systolic dysfunction

of the left ventricle that leads to symptomatic heart failure. Several lines of evidence

suggest that circulating and myocardial renin-angiotensin systems (RAS) are involved in the

regulation of the structural remodeling of the nonmyocyte compartment, including the

cardioprotective effects of angiotensin converting enzyme (ACE) inhibition that was found

to prevent myocardial fibrosis in the rat with renovascular hypertension. In cultured adult

rat cardiac fibroblasts angiotensin II was shown to directly stimulate collagen synthesis and

to inhibit collagenase activity, which is the key enzyme for collagen degradation, that would

lead to collagen accumulation. In the spontaneously hypertensive rat, an appropriate

experimental model for primary hypertension in man, left ventricular hypertrophy could be

regressed and abnormal myocardial diastolic stiffness due to interstitial fibrosis could be

restored to normal by inhibition of the myocardial RAS. These antifibrotic or

cardioreparative effects of ACE inhibition that occurred irrespective of blood pressure

normalization may be valuable in reversing left ventricular diastolic dysfunction in

hypertensive heart disease (Au).

Au: Hori M; Sato H; Fukunami M; Houki N.

Ad: First Department of Medicine, Osaka University School of Medicine.

Ti: Pathophysiology of cytoskeleton and extracellular matrix in failing myocardium.

So: Nippon Rinsho; 51(5):1191-7, 1993 May.

Ab: Cytoskeleton of myocytes and extracellular matrix play an essential role for

maintaining cellular function. Alterations in humoral factors observed in heart failure, e.g.,

excess of plasma norepinephrine and angiotensin II, injure the microtubule structure

probably through Ca overload and increase the collagen synthesis of the cardiac fibroblast.

Recent studies demonstrated that network structures of microtubules and intermediate

filaments are disrupted in the myocardium obtained from patients with heart failure.

Changes in cytoskeletons and extracellular matrix may affect the contractile function, since

they organize the intra- and inter-cellular architectures. Pathophysiological roles of

cytoskeletons and extracellular matrix in failing hearts deserve further studies (Au).

Au: Makino N; Matsui H; Masutomo K; Hata T; Yanaga T.

Ad: Department of Bioclimatology and Medicine, Kyushu University, Beppu, Japan.

Ti: Effect of angiotensin converting enzyme inhibitor on regression in cardiac hypertrophy.

So: Mol Cell Biochem; 119(1-2):23-8, 1993 Feb 17.

Ab: Cardiac hypertrophy in rats was produced by aortic banding for 6 weeks and regression

of hypertrophy in these experimental animals was induced by administration of angiotensin

converting enzyme inhibitor, enalapril (10 mg/kg/day) for 6 weeks. The left ventricular

muscle mass and systolic pressure were decrease upon treating the hypertrophied rats with

enalapril. This drug also decreased the number of alpha 1-adrenoceptors in hypertrophied

myocardium without any changes in beta-adrenoceptors. The regression of cardiac

hypertrophy in spontaneously hypertensive rats by enalapril for 10 weeks was not

associated with any alterations in alpha 1-adrenoceptors in hypertrophied myocardium, but

was decreased in beta-adrenoceptors. Effects of enalapril on extracellular matrix in the

myocardium was also observed in regression of hypertrophy in which the type III collagen

mRNA expression and collagen contents were reduced in comparison with those of

hypertrophied myocardium. These results indicate that regression of cardiac hypertrophy is

not always associated with a decrease in the number of alpha 1-adrenergic receptors and

that the beneficial effects of enalapril in the hypertrophied heart in aortic banding

animals may be of some specific nature (Au).

Au: Rinehart AR; Mallya S; Simon SR.

Ad: Department of Biochemistry, SUNY at Stony Brook 11794-8691.

Ti: Human alpha 1-proteinase inhibitor binds to extracellular matrix in vitro.

So: Am J Respir Cell Mol Biol; 9(6):666-79, 1993 Dec.

Ab: alpha 1-Proteinase inhibitor (alpha 1-PI) is the major endogenous inhibitor of human

leukocyte elastase (HLE). We have employed two different methods to quantitate the

binding of alpha 1-PI to extracellular matrix (ECM), composed of 51% glycoproteins and

proteoglycans, 37% types I and III collagen, and 12% elastin, derived from rat heart smooth

muscle cells. alpha 1-PI is tightly bound to ECM via a saturable adsorption process; the

bound protein fails to dissociate from the matrix after repeated washing. Binding of alpha

1-PI is unaffected by the prior removal of ECM glycoproteins with trypsin. Binding to ECM

is not decreased in the presence of high salt but is decreased at low pH. A 40-fold excess of

unlabeled alpha 1-PI displaces only 50% of [125I]alpha 1-PI prebound to ECM. A 30%

decrease in the levels of alpha 1-PI bound to ECM is observed after DTT washes of ECM

preincubated with alpha 1-PI or when alpha 1-PI is modified with iodoacetamide prior to

incubation with ECM, implying that a fraction of bound alpha 1-PI is covalently linked to

ECM via disulfide bond formation. Moreover, high molecular weight complexes between

[125I]alpha 1-PI and ECM components can be visualized by SDS-PAGE under

nonreducing conditions but disappear upon reduction. Approximately 50% of the total

alpha 1-PI bound covalently or noncovalently to ECM retains the ability to inhibit HLE-

mediated ECM proteolysis. alpha 1-PI-HLE complexes bound to ECM can be visualized by

SDS-PAGE following the addition of HLE to ECM that was pretreated with [125I]alpha 1-

PI. alpha 1-PI from normal plasma or serum also binds to ECM with retention of

immunoreactivity and partial retention of inhibitory activity. However, ECM pretreated

with alpha 1-PI-deficient serum retains no HLE-inhibitory activity (Au).

Au: Pardo Mind n FJ; Panizo A.

Ad: Department of Pathology, Cl¡nica Universitaria, University of Navarra, Pamplona,

Spain.

Ti: Alterations in the extracellular matrix of the myocardium in essential hypertension.

So: Eur Heart J; 14 Suppl J:12-4, 1993 Nov.

Ab: Hypertension produces myocyte hypertrophy and increases the extracellular matrix. In

order to determine the composition of the extracellular matrix we studied the hearts from 14

hypertensive patients by immunohistochemistry using antibodies against collagen I, III, IV

and V, fibronectin, myoglobin, muscular specific actin, Factor VIII, CD 34 and vimentin.

The myocardium showed a focal increase in fibronectin, collagen I and III and diffuse

deposition of laminin, collagen IV and V. Cells positive for vimentin, Factor VIII and CD

34 were also increased, but with considerable variation from case to case. We found no

relation between matrix variation and the degree of hypertension or the time elapsed from

the beginning of the disease. We conclude that the main role of the matrix in hypertension

may be remodelling of the heart so that it entraps muscle fibres and increases their

contractility (Au).

Au: Brilla CG; Reams GP; Maisch B; Weber KT.

Ad: Division of Cardiology, Philipps-University of Marburg, Germany.

Ti: Renin-angiotensin system and myocardial fibrosis in hypertension: regulation of the

myocardial collagen matrix.

So: Eur Heart J; 14 Suppl J:57-61, 1993 Nov.

Ab: The cardiac interstitium is composed of non-myocyte cells embedded in a highly

organized extracellular matrix containing a three-dimensional collagen network which

serves to maintain the architecture of the myocardium and determines myocardial stiffness.

In hypertensive heart disease, a heterogeneity in myocardial structure, created by the altered

behaviour of cardiac fibroblasts responsible for collagen synthesis and degradation, can

explain the appearance of diastolic and ultimately systolic dysfunction of the left ventricle.

In vivo, circulating and myocardial renin-angiotensin systems (RAS) were found to be

involved in the regulation of the structural remodelling of the cardiac interstitium. In vitro,

in cultured adult rat cardiac fibroblasts, angiotensin II was shown to stimulate collagen

synthesis and to inhibit collagenase activity, which is the key enzyme for collagen

degradation. In the SHR-model of primary hypertension, left ventricular hypertrophy could

be regressed and abnormal myocardial diastolic stiffness, due to interstitial fibrosis, could

be restored to normal by inhibition of the myocardial RAS. These antifibrotic or

cardioreparative effects of ACE inhibition that occurred irrespective of blood pressure

normalization may be valuable in reversing left ventricular diastolic dysfunction in

hypertensive heart disease (Au).

Au: Engelmann GL.

Ad: Department of Medicine, Loyola University Chicago, Stritch School of Medicine,

Maywood, IL 60153.

Ti: Coordinate gene expression during neonatal rat heart development. A possible role for

the myocyte in extracellular matrix biogenesis and capillary angiogenesis.

So: Cardiovasc Res; 27(9):1598-605, 1993 Sep.

Ab: OBJECTIVE: Neonatal heart development is a period of active extracellular matrix

deposition and capillary angiogenesis which follows the cessation of ventricular myocyte

proliferation. The aim was to determine whether coordinate expression of growth factors by

the ventricular myocyte could function to inhibit myocyte proliferation directly as well as

indirectly by paracrine stimulation of non-myocyte extracellular matrix deposition and

capillary angiogenesis. METHODS: Immunohistochemistry and northern blot

hybridisations were performed on ventricular samples from fetal to mature animals of the

spontaneously hypertensive (SHR) and normotensive control Wistar Kyoto (WKY)

strains. RESULTS: Ventricular expression of types I, III, and IV collagen genes reached

their ®maximum® within the first 2-3 postnatal weeks and then rapidly declined.

Expression of TGF beta 3 and SPARC were found to precede and accompany the changes

in extracellular matrix gene expression during this same developmental period. TGF beta 3

was immunolocalised to fetal cardiomyocytes with very limited expression in

neonatal/adult non-myocytes. Associated with the neonatal expression of TGF beta variants,

transcripts for the type 2 IGF receptor gradually declined over the first three postnatal

weeks. Myocyte TGF beta gene expression, latent TGF beta release, and paracrine

mechanisms of action could be facilitated by residual type 2 IGF receptor expression to help

mediate stimulation of non-myocyte extracellular matrix synthesis and deposition.

CONCLUSIONS: Expression of select growth factors, growth factor receptors, and

components of the extracellular matrix appear to be highly coordinated during ventricular

remodelling which occurs during neonatal heart development. A paradigm is presented

which integrates the expression patterns of various myocyte derivedstimuli and their

postulated impact on formation of the structural components of the neonatal heart by

modulation of myocyte and non-myocyte cell types (Au).

Au: Tyagi SC; Ratajska A; Weber KT.

Ad: Department of Internal Medicine, University of Missouri-Columbia 65212.

Ti: Myocardial matrix metalloproteinase(s): localization and activation.

So: Mol Cell Biochem; 126(1):49-59, 1993 Sep 8.

Ab: Matrix metalloproteinases (MMPs) and neutrophil elastase (NE) may each contribute

to fibrillar collagen degradation in various disease states. Little, however, is known about

the activation and localization of MMP in the heart. Accordingly, we extracted MMP and

examined mechanisms of proMMP activation in whole tissue extracts of the adult rat

myocardium. Incubation of extracts with serine proteases (i.e., trypsin or neutrophil

elastase) at 37 degrees C resulted in a time-dependent activation of proMMPs. Based on

immunoblot and measurements of MMP activity by zymography, the molecular weight of

active MMP was deduced to be 52 kDa. The second-order rate constant for activation of

proMMP by serine protease was 5.5 +/- 0.2 x 10(5) M-1min-1 and for oxidized glutathione

(GSSG) 1.5 +/- 0.1 M-1min-1. Incubation of the extract with both serine protease and

GSSG increased the rate of activation 30-fold. Based on reverse zymographic analysis of

collagenase inhibition, tissue inhibitors of metalloproteinases were identified. Indirect

immunofluorescence localized proMMPs/MMPs to the endothelium and subendothelial

space of the endocardium and throughout the interstitial space found between groups of

muscle fibers. These results suggest that the mechanism of activation of MMPs by either a

serine protease and by oxidizing, thiol-modifying reagents are mechanistically different

and the presence of either a serine protease or GSSG synergistically increase the rate of

activation of proMMPs. Our results also suggest that MMPs may be regulated by its own

endogenous inhibitors. The contribution of this proteolytic enzyme to tissue remodeling and

wound healing responses that occur in various diseases states remains to be established

(Au).

Au: Okada H.

Ad: Hokkaido University School of Medicine, Sapporo, Japan.

Ti: An investigation of the collagen in cardiomyopathic hamsters.

So: Hokkaido Igaku Zasshi; 68(6):894-905, 1993 Nov.

Ab: Extensive fibrosis is remarkable in cardiomyopathy. The purpose of this study is to

characterize the collagen, one of the chief elements of the extracellular matrix of hereditary

cardiomyopathic hamsters, and to examine the participation of the collagen in the

occurrence and the progression of the cardiomyopathy. BIO53.58 (5, 11, 22 weeks) was

used as the model of the dilated cardiomyopathy and BIO14.6 (20, 30 weeks) was used as

the model of the hypertrophic cardiomyopathy F1b was used as the control. The collagen

content was almost constant at any age in F1b, but increased with aging in BIO53.58 and

BIO14.6. Type III collagen increased significantly in BIO53.58 at 11 weeks and BIO14.6 at

20 weeks. Type V collagen decreased significantly in BIO14.6 at 30 weeks. Acetic acid

solubility of collagen decreased in BIO53.58 and BIO14.6 with the progression of the

fibrosis, but not in F1b. Reducible crosslinks showed the tendency to decrease in BIO53.58

progressively. Histologically thick collagen fiber increased in BIO53.58 and BIO14.6.

These findings indicate that in the early phase of the cardiomyopathy the extracellular

matrix of the myocardium has characteristics that of the immature tissues which are rich in

type III collagen. In later phase, the matrix resembles that of hard tissues whose collagen is

mainly of type I collagen and have low solubility. It is considered that the increase of the

thick collagen fiber combined firmly in heart may affect the diastolic and the systolic

function in addition to the loss of the cardiac muscle fiber by the degeneration and the

necrosis (Au).

MATRIZ EXTRACELULAR X CORACAO/MIOCARDIO

Au: Sinning AR; Krug EL; Markwald RR.

Ad: Department of Anatomy, University of Mississippi Medical Center, Jackson.

Ti: Multiple glycoproteins localize to a particulate form of extracellular matrix in regions of

the embryonic heart where endothelial cells transform into mesenchyme.

So: Anat Rec; 232(2):285-92, 1992 Feb.

Ab: Cells derived from an epithelial-mesenchymal transformation within the

atrioventricular canal and outflow tract are involved in the partitioning of the early

embryonic heart into a four-chambered organ. This transformation process has been

shown to proceed from an inductive interaction between the myocardium and competent,

target endothelial cells within these regions of the heart. Interestingly,

immunohistochemistry revealed the presence of fibronectin-positive particulates within the

matrix of mesenchyme-forming regions (Mjaatvedt et al., 1987). This particulate matrix is

extractable by EDTA and can elicit the epithelial-mesenchymal transformation in culture

(Mjaatvedt and Markwald, 1989). Analysis of EDTA extracts of embryonic heart tissue

revealed the presence of fibronectin and about 40 unidentified proteins, 6 of which

appeared to be enriched in the biologically active 100,000g pellet fraction (Mjaatvedt and

Markwald, 1989). Based on these and other data we have proposed that the particulate

matrix is composed of a multicomponent complex of fibronectin and one or more of the

low-molecular-weight proteins in this pellet. The purpose of the present study was to begin

a biochemical characterization of the nonfibronectin proteins thought to be present in the

matrix particulates. Given that many matrix constituents are glycoproteins, lectins were

used to initially characterize the particulate constituents. Of the lectins tested, soybean

agglutinin (SBA) was found to be specific only for matrix particulates. Histochemical

analyses showed that SBA and antibodies against fibronectin colocalized regionally and

temporally to the same matrix particulates in embryonic heart tissue.(ABSTRACT

TRUNCATED AT 250 WORDS) (Au).

Au: Speiser B; Weihrauch D; Riess CF; Schaper J.

Ad: Max-Planck-Institute, Department of Experimental Cardiology Bad Nauheim, Federal

Republic of Germany.

Ti: The extracellular matrix in human cardiac tissue. Part II: Vimentin, laminin, and

fibronectin.

So: Cardioscience; 3(1):41-9, 1992 Mar.

Ab: In continuation of our previous work describing the localization of the collagens type I,

III, VI, and IV the present study describes the localization of vimentin, laminin, and

fibronectin in human myocardium obtained as left ventricular needle biopsies during

cardiac surgery. Myocardium from normal pigs served for comparison. Monoclonal

antibodies against the various proteins were used on frozen sections, labeled with

fluorescein and viewed in the fluorescence microscope. Vimentin, the intermediate filament

of mesenchymal cells, is present in fibroblasts, fibrocytes, and endothelial cells. Laminin is

observed in the basal membrane of myocytes, smooth muscle and endothelial cells. The

staining intensity for the B1-chain is higher in and around myocytes as compared with the

B2-chain antibody, but more blood vessels were stained with the latter. The antibody

against the A-chain only stained the basal lamina of vascular cells but not that of myocytes.

Fibronectin was localized homogeneously throughout the extracellular space as matrix

material in which the cellular elements and the various other proteins such as collagens are

embedded. Intracellular staining in myocytes (T-tubules) was commonly observed. Both

parts of this study show the distribution of extracellular proteins in normal human cardiac

tissue and are intended to be the basis for investigations of pathological changes in diseased

human myocardium (Au).

Au: Yost HJ.

Ad: Department of Cell Biology and Neuroanatomy, University of Minnesota, Minneapolis

55455.

Ti: Regulation of vertebrate left-right asymmetries by extracellular matrix.

So: Nature; 357(6374):158-61, 1992 May 14.

Ab: The vertebrate body is organized along three geometric axes: anterior-posterior, dorsal-

ventral and left-right. Left-right axis formation, displayed in heart and gut development, is

the least understood, even though it has been studied for many years. In Xenopus laevis

gastrulae, a fibronectin-rich extracellular matrix is deposited on the basal surface of

ectoderm cells over which cardiac and visceral primordia move during development. Here I

report experiments in which localized perturbation of a small patch of extracellular matrix

by microsurgery was correlated with localized randomization of left-right asymmetries.

Global perturbation of the extracellular matrix by microinjection of Arg-Gly-Asp peptides

or heparinase into the blastocoel resulted in global randomization of left-right asymmetries.

From these observations, I suggest that left-right axial information is contained in the

extracellular matrix early in development and is independently transmitted to cardiac and

visceral primordia (Au).

Au: Brilla CG; Maisch B; Weber KT.

Ad: Division of Cardiology, Philipps University of Marburg, Germany.

Ti: Myocardial collagen matrix remodelling in arterial hypertension.

So: Eur Heart J; 13 Suppl D:24-32, 1992 Sep.

Ab: The cardiac interstitium is composed of non-myocyte cells and a structural fibrillar

protein network which plays a dominant role in governing the structure, architecture, and

mechanical behaviour of the myocardium. Herein we review the fibrillar collagen network,

its various components, and the functions they serve in the normal and structurally

remodelled myocardium in arterial hypertension. The heterogeneity in myocardial structure,

created by the altered behaviour of non-myocyte cells, particularly cardiac fibroblasts,

which are responsible for collagen synthesis or degradation and thereby fibrous tissue

accumulation, is a major determinant for the appearance of diastolic dysfunction and

ultimately systolic myocardial failure. Regulatory mechanisms related to this fibrous tissue

response are reviewed to draw attention to the hitherto neglected role of cardiac fibroblasts

in mediating adverse structural remodelling of the myocardium and showing how this can

be prevented through the use of pharmacological agents that interfere with the regulation of

the myocardial collagen matrix. Several lines of evidence suggest that circulating and tissue

renin-angiotensin-aldosterone systems (RAAS) are involved in the structural remodelling of

the non-myocyte compartment. These include the cardioprotective effects of angiotensin

converting enzyme (ACE) inhibition and aldosterone receptor antagonism that were found

to prevent myocardial fibrosis in the rat with renovascular hypertension. In the rat with

genetic hypertension, established left ventricular hypertrophy and abnormal myocardial

diastolic stiffness due to interstitial fibrosis, RAAS inhibition resulted in restoration of

myocardial structure and function to normal.(ABSTRACT TRUNCATED AT 250

WORDS) (Au).

Au: G¢mez RM; Castagnino CG; Berr¡a MI.

Ad: Department of Microbiology, Faculty of Medicine, University of Buenos Aires,

Argentina.

Ti: Extracellular matrix remodelling after coxsackievirus B3-induced murine myocarditis.

So: Int J Exp Pathol; 73(5):643-53, 1992 Oct.

Ab: Weanling inbred Balb/c mice were intraperitoneally inoculated with a myocarditic

variant of coxsackievirus B3. At days 1, 2, 4, 6, 8, 10, 14, 24 and 30 post-infection (p.i.),

myocardial tissue was harvested for viral infectivity titrations and histological studies,

including routine techniques (haematoxylin-eosin, Masson trichrome and von Kossa) and

specialized procedures (silver impregnation for reticulin, picrosirius red stain for collagen

and immunoperoxidase labelling for laminin). Virus was isolated as from day 2, reached

maximal infectivity at days 6-8 and decreased gradually to become undetectable by day 14.

Early histological findings during the 1st week consisted mainly of scattered foci of necrotic

myocytes showing calcium deposits; slight mononuclear cell infiltration and fragmentation

of both reticulin fibres and pericellular laminin were also present. From the 2nd up to 4th

week p.i., inflammatory reaction abated concomitantly with the gradual development of

fibrosis, as evidenced by reticulin fibre thickening, irregular laminin distribution and

collagen fibre increase. Our results suggest that viral-induced necrosis is able to trigger

marked extracellular matrix remodelling even in the case of minimal inflammation (Au).

MATRIZ EXTRACELULAR X CORACAO/MIOCARDIO

Au: Tart RC; van de Rijn I.

Ad: Wake Forest University Medical Center, Winston-Salem, North Carolina 27103.

Ti: Analysis of adherence of Streptococcus defectivus and endocarditis-associated

streptococci to extracellular matrix.

So: Infect Immun; 59(3):857-62, 1991 Mar.

Ab: Pathogenesis of nutritionally variant streptococcal (NVS) endocarditis initiates with

bacterial attachment to and colonization of the damaged heart valve surface. Underlying

extracellular matrix (ECM) exposed to the environment during damage to cardiac

endothelium provides additional receptors that could be involved in bacterial adherence.

The ability of NVS and endocarditis-associated streptococci to bind ECM was investigated

by using an enzyme-linked immunosorbent assay system that incorporated ECM secreted by

baby hamster kidney and human umbilical vein endothelial cells in culture. Streptococcus

defectivus, the major species isolated from NVS endocarditis cases, bound ECM of

fibroblasts and endothelial cells, indicating that the ECM molecule involved in the binding

was a common constituent of diverse matrices. The specific binding of S. defectivus to

ECM was demonstrated by saturation binding and specific antibody inhibition studies. Of

the 15 S. defectivus strains analyzed, 13 bound ECM, whereas Streptococcus adjacens and

NVS serotype III strains were unable to bind the matrix. This selective binding suggested

that S. defectivus binds to heart valves through a mechanism different from those of other

NVS in subacute bacterial endocarditis. A survey of non-NVS streptococcal endocarditis

isolates demonstrated that S. mutans, S. mitis, S. sanguis, and S. faecalis also bound ECM,

whereas other viridans species were unable to bind the matrix (Au).

Au: Mjaatvedt CH; Krug EL; Markwald RR.

Ad: Department of Physiology, Johns Hopkins University School of Medicine, Baltimore,

Maryland 21205.

Ti: An antiserum (ES1) against a particulate form of extracellular matrix blocks the

transition of cardiac endothelium into mesenchyme in culture.

So: Dev Biol; 145(2):219-30, 1991 Jun.

Ab: The epithelial-mesenchymal transition of cardiac endothelium is a critical

developmental event in the formation of valvular and septal anlagen. We have

demonstrated previously that this event can be mimicked in culture by treating

atrioventricular canal (AV) endothelium with EDTA-soluble proteins extracted from

embryonic heart tissue. This activity was fractionated by ultracentrifugation of the EDTA

extract, indicating that the critical proteins existed as a multicomponent complex. Based on

these results we propose that: (1) the in vitro particulates in EDTA extracts correspond to

an observed particulate form of extracellular matrix within the myocardial basement

membrane (MBM) of mesenchyme-forming regions and (2) one or more of the proteins in

the MBM particulates function to elicit the epithelial-mesenchymal transition. To test these

hypotheses we utilized an antiserum, termed ES1, prepared against EDTA-extractable

particulates from embryonic chick hearts. Both ES1 and an anti-fibronectin monoclonal

antibody (M3H) co-localized in situ to particles within the MBM; however, no ES1

reactivity towards fibronectin could be detected by ELISA or immunoblot analysis. The

ES1-positive MBM particulates were removed by extraction with EDTA, but not with

PBS, indicating a divalent cation-mediated association of the constituent proteins. ES1

antibodies recognized two major (28 and 46 kDa) and three minor (93, 109, and 180 kDa)

proteins on immunoblots of EDTA-extractable proteins. When tested in culture, ES1

antiserum inhibited the formation of mesenchyme from AV endothelium in a dose-

dependent manner, while M3H did not. These results are consistent with an active role for

one or more of the ES1 antigens in initiating the formation of AV mesenchyme. The

localization of ES1 antigens to the extracellular matrix at other dynamic interfaces, e.g.,

ectoderm/neural tube and limb bud ectoderm/mesoderm, point to a potentially general

importance of ES1 antigens in mediating similar developmental interactions (Au).

Au: Fransen ME; Lemanski LF.

Ad: Department of Anatomy and Cell Biology, College of Medicine, State University of

New York, Syracuse 13210.

Ti: Extracellular matrix of the developing heart in normal and cardiac lethal mutant

axolotls, Ambystoma mexicanum.

So: Anat Rec; 230(3):387-405, 1991 Jul.

Ab: As part of an ongoing study of heart development in normal and cardiac lethal mutant

axolotls (Mexican salamanders) we examined the extracellular matrix (ECM) by

microscopical methods. With scanning electron microscopy we are unable to detect ECM

on the apical surface of cells of the early cardiogenic mesoderm. During the period of

lateral plate migration, which coincides with the period of cardiogenic induction of

mesoderm by anterior endoderm, there is little ECM, aside from some microfibrils, on the

basal surface of the endoderm or mesoderm of the pharyngeal region. Later, a basal lamina

(BL) is found on the endoderm and along portions of the developing endocardial and

myocardial tubes. By the time of heartbeat initiation the BLs are complete and invested

with striated collagen-like fibrils that are sparsely distributed in the ®cardiac jelly¯ of

normal and mutant hearts. Striated fibril deposition, which increases with time, is generally

random in orientation, with the exception of some regions where there is a preferred

directionality. During the post-hatching period striated fibrils appear in the subepicardial

space. In addition, branching fibers that are probably elastin appear in the bulbus arteriosus.

In these later stages the density of fibrils in the cardiac lethal mutant heart is much less than

normal. Indirect immunofluorescent microscopy reveals laminin and fibronectin in the basal

laminae of the endocardial and myocardial tubes of both normal and cardiac lethal mutant

hearts. In addition, punctate and fibrillar staining for fibronectin, and punctate staining for

laminin are found in the cardiac jelly. These matrix proteins are not abundant at the apical

(exterior) surface of the myocardium until the epicardium appears.(ABSTRACT

TRUNCATED AT 250 WORDS) (Au).

Au: Hilenski LL; Terracio L; Borg TK.

Ad: Department of Pathology, University of South Carolina, Columbia 29208.

Ti: Myofibrillar and cytoskeletal assembly in neonatal rat cardiac myocytes cultured on

laminin and collagen.

So: Cell Tissue Res; 264(3):577-87, 1991 Jun.

Ab: Neonatal rat cardiomyocytes were cultured on extracellular matrix components laminin

and collagens I + III to examine effects of extracellular matrix on the assembly of

cytoskeletal proteins during myofibrillogenesis. Myofibril assembly was visualized by

immunofluorescence of marker proteins for myofibrils (f-actin for I bands and alpha-actinin

for Z bands), focal adhesions (vinculin), and transmembrane extracellular matrix receptors

(beta 1 integrin) as cells spread for various times in culture. By 4 h in culture, f-actin

appeared organized into nonstriated stress-fiber-like structures while alpha-actinin, vinculin

and beta 1 integrin were localized in small streaks and beads. Subsequently, striated

patterns were observed sequentially in the intracellular cytoskeletal components alpha-

actinin, vinculin, f-actin, and then in the transmembrane beta 1 integrin receptor. These data

support an earlier model for sarcomerogenesis in which stress-fiber-like structures serve as

initial scaffolds upon which alpha-actinin and then vinculin-containing costameres are

assembled. This sequential and temporal assembly was the same on both laminin and

collagens I + III. A quantitative difference, however, was apparent on the 2 matrices. There

was an increased appearance on collagens I + III of rosettes (also called podosomes or

cortical actin-containing bodies in other cells) which consisted of an f-actin core surrounded

by alpha-actinin, vinculin and beta 1 integrin rims. The increased incidence of rosettes in

neonatal myocytes on collagens I + III suggests that these cytoskeletal complexes are

involved in recognition and interaction with extracellular matrix components (Au).

Au: Baysal K; Brierley GP; Novgorodov S; Jung DW.

Ad: Department of Medical Biochemistry, Ohio State University, Columbus 43210.

Ti: Regulation of the mitochondrial Na+/Ca2+ antiport by matrix pH.

So: Arch Biochem Biophys; 291(2):383-9, 1991 Dec.

Ab: The effect of matrix pH (pHi) on the activity of the mitochondrial Na+/Ca2+ antiport

has been studied using the fluorescence of SNARF-1 to monitor pHi and Na(+)-dependent

efflux of accumulated Ca2+ to follow antiport activity. Heart mitochondria respiring in a

KCl medium maintain a large delta pH (interior alkaline) and show optimal Na+/Ca2+

antiport only when the pH of the medium (pH0) is acid. Addition of nigericin to these

mitochondria decreases delta pH and increases the membrane potential (delta psi).

Nigericin strongly activates Na+/Ca2+ antiport at values of pH0 near 7.4 but inhibits

antiport activity at acid pH0. When pHi is evaluated in these protocols, a sharp optimum

in Na+/Ca2+ antiport activity is seen near pHi 7.6 in the presence or absence of nigericin.

Activity falls off rapidly at more alkaline values of pHi. The effects of nigericin on

Na+/Ca2+ antiport are duplicated by 20 mM acetate and by 3 mM phosphate. In each case

the optimum rate of Na+/Ca2+ antiport is obtained at pHi 7.5 to 7.6 and changes in antiport

activity do not correlate with changes in components of the driving force of the reaction

(i.e., delta psi, delta pH, or the steady-state Na+ gradient). It is concluded that the

Na+/Ca2+ antiport of heart mitochondria is very sensitive to matrix [H+] and that changes

in pHi may contribute to the regulation of matrix Ca2+ levels (Au).

Au: Sanchez-Quintana D; Garcia-Martinez V; Macias D; Hurle JM.

Ad: Departamento de Ciencias Morfol¢gicas, Facultad de Medicina, Badajoz, Spain.

Ti: Structural arrangement of the extracellular matrix network during myocardial

development in the chick embryo heart.

So: Anat Embryol (Berl); 184(5):451-60, 1991.

Ab: We analyzed the extracellular matrix and the connective tissue of the developing chick

myocardium (®myocardial interstitium¯ ). The importance of this myocardial element for

heart function has been well documented both for the normal and pathologic adult hearts.

However, little information is available on the organization of the embryonic myocardial

interstitium and its modifications during development and increasing intracardiac pressure.

In the present study we used light and scanning electron microscopic techniques, and lectin

probes to study the interstitium of the ventricular myocardium of chick embryos from stage

29 (day 6 of development) until hatching. Our observations trace the progressive

appearance and organization of the elements of the extracellular matrix, comprising the

epimysium, perimysium and endomysium, which form a well-defined architectural

network. Finally, we discuss the role of these elements of the extracellular matrix and their

possible relation with the biomechanical properties of developing heart (Au).

Au: Speiser B; Riess CF; Schaper J.

Ad: Max-Planck-Institute, Department of Experimental Cardiology, Bad Nauheim,

Germany.

Ti: The extracellular matrix in human myocardium: Part I: Collagens I, III, IV, and VI.

So: Cardioscience; 2(4):225-32, 1991 Dec.

Ab: The composition of the extracellular matrix in normal human myocardium obtained at

open-heart surgery was investigated using monoclonal antibodies against the collagens I,

III, IV, and VI, and fluorescence microscopy. The aim of the study was to provide

information on normal myocardium that could be used in the evaluation of pathological

changes. Porcine myocardium was used for comparison, and both tissues showed a perfect

agreement of the results, apart from collagen IV. This was negative in pig myocardium, due

to the species specificity of the antibody. Collagens I and III were localized in the

extracellular space as either coarse or fine fibrillar structures; the cellular elements of the

interstitium, except for the endothelial cells, were also stained. Labeling for collagen VI

was much finer than for the other collagens, and was present throughout the interstitium.

Collagen IV stained the basement membranes of myocytes and capillary endothelial cells,

and also labeled the T-tubular system in the myocytes. The second part of this

communication will describe the localization of fibronectin, laminin and vimentin in

normal human myocardium (Au).

Au: Garcia-Martinez V; Sanchez-Quintana D; Hurle JM.

Ad: Departamento de Ciencias Morfol¢gicas, Facultad de Medicina, Universidad de

Extremadura, Badajoz, Espa¤a.

Ti: Histochemical and ultrastructural changes in the extracellular matrix of the developing

chick semilunar heart valves.

So: Acta Anat (Basel); 142(1):87-96, 1991.

Ab: The present study analyzes the composition and organization of the extracellular matrix

(ECM) and its changes in the course of development of the chick embryo semilunar heart

valves. In the present work we have employed chick embryos from stage 29 until

hatching, using silver and picrosirius red staining, lectin probes and light and transmission

electron microscopy. Our results show that during semilunar valve development a series of

elements arise and are organized in the ECM which seem to be more closely related to the

maintenance of the structural and biomechanical properties of the valvular leaflets than

with morphogenetic processes per se (Au).

Au: Schmiedl A; Bach F; Richter J; Schnabel PA; Bretschneider HJ.

Ad: Zentrum Anatomie, Abteilung Elektronenmikroskopie, Universit„t G”ttingen, BRD.

Ti: Morphometric evaluation of the myocardial interstitial space after physical and chemical

fixation. A light-microscopic study on the left ventricle of canine hearts.

So: Acta Anat (Basel); 142(4):321-5, 1991.

Ab: The interstitial space, separated into tissue clefts and interstitium within bundles of

myocytes of left canine ventricle, was investigated qualitatively and morphometrically after

using different methods of fixation following aortic cross clamping and 10 min of ischemia

at 5 degrees C. In frozen sections, the size of tissue clefts is significantly lower than in

semithin sections after immersion fixation. The interstitium within bundles of myocytes

shows similar values independent of the fixation technique (r = 0.83). This constancy

permits a free choice between the two fixation techniques, there being no loss of

information from the material investigated (Au).

MATRIZ EXTRACELULAR X CORACAO/MIOCARDIO

Au: Orekhov AN; Tertov VV; Kudryashov SA; Smirnov VN.

Ad: Institute of Experimental Cardiology, USSR Cardiology Research Center, Moscow.

Ti: Triggerlike stimulation of cholesterol accumulation and DNA and extracellular matrix

synthesis induced by atherogenic serum or low density lipoprotein in cultured cells.

So: Circ Res; 66(2):311-20, 1990 Feb.

Ab: A 72-hour incubation of cultured cells with blood sera or plasma of patients suffering

from coronary heart disease (CHD) with angiographically assessed coronary atherosclerosis

caused a threefold to fourfold elevation of intracellular cholesterol. An elevated cholesterol

level in the cells precultured with patients' sera was retained several days after the removal

of the examined serum from culture. The accumulation of intracellular cholesterol was

accompanied by enhanced synthesis of DNA, total protein, collagen, sulfated

glycosaminoglycans, and hyaluronic acid. Enhanced DNA and total protein synthesis was

retained for at least 9 days after the serum had been removed from culture. The obtained

results suggest that the sera of CHD patients possess an atherogenic potential that manifests

itself at the arterial cell level in the stable stimulation of atherosclerotic cellular processes:

proliferation, lipidosis, and fibrosis. The examined sera of healthy donors were devoid of

such an atherogenic potential. The low density lipoprotein (LDL) fraction (density, 1.030-

1.050 g/cm3) obtained from an atherogenic serum had the same atherogenic potential as a

whole serum. Atherosclerotic alterations in cultured intimal cells caused by atherogenic

LDL were retained for at least 3 days after the removal of the lipoprotein from culture.

Preincubation of intimal cells with LDL obtained from healthy donors had no effect on the

intracellular cholesterol level or the synthesis of DNA and extracellular matrix. One may

assume that the atherogenic potential of CHD patients' sera is related to the presence of

LDLs that are qualitatively different from the LDL of healthy subjects (Au).

Au: Covell JW.

Ad: Department of Medicine, University of California, San Diego 92093.

Ti: Factors influencing diastolic function. Possible role of the extracellular matrix.

So: Circulation; 81(2 Suppl):III155-8, 1990 Feb.

Au: Golan M; Modan M; Lavee J; Martinowitz U; Savion N; Goor DA; Mohr R.

Ad: Department of Cardiac Surgery, Chaim Sheba Medical Center, Tel Aviv, Israel.

Ti: Transfusion of fresh whole blood stored (4 degrees C) for short period fails to improve

platelet aggregation on extracellular matrix and clinical hemostasis after cardiopulmonary

bypass.

So: J Thorac Cardiovasc Surg; 99(2):354-60, 1990 Feb.

Ab: It has recently been shown that the hemostatic effect of 1 unit of fresh whole blood is

equivalent to the effect of 8 to 10 platelet units. This study was designed to evaluate the

effect of short periods of cold (4 degrees C) storage on the hemostatic effect of fresh whole

blood transfusion in 36 patients immediately after cardiopulmonary bypass. Twelve patients

(group A) received unrefrigerated fresh whole blood, 12 (group B) received fresh whole

blood after 5 hours' storage at 4 degrees C, and 12 (group C) after 24 hours' storage at 4

degrees C. For evaluation of platelet function, a method with an extracellular matrix and an

electron microscope was used. The platelet function was graded from 1 to 4, with grade 4

being normal aggregation. Postoperatively, group A patients bled less than groups B and C

(267 +/- 42 versus 397 +/- 72 and 601 +/- 172 ml/24 hr, respectively, p less than 0.001) and

therefore received fewer blood units (1.4 +/- 0.5 versus 2 +/- 0.9 and 3 +/- 1.4, respectively,

p less than 0.01). Five patients of group A (42%) reached grade A aggregation after

transfusion of unstored fresh whole blood, compared with two (17%) of group B and none

(0%) of group C (p less than 0.01). Posttransfusion platelet count and mean platelet volume

were not significantly different in the three groups. We conclude that storage at 4 degrees C,

even for a short period of 5 hours, diminishes the hemostatic effect of fresh whole blood by

decreasing platelet aggregability (Au).

Au: Weber KT; Pick R; Silver MA; Moe GW; Janicki JS; Zucker IH; Armstrong PW.

Ad: Cardiovascular Institute, Michael Reese Hospital, University of Chicago Pritzker

School of Medicine.

Ti: Fibrillar collagen and remodeling of dilated canine left ventricle.

So: Circulation; 82(4):1387-401, 1990 Oct.

Ab: To test the hypothesis that in the failing volume-overloaded ventricle, the extracellular

matrix and fibrillar collagen in particular are major determinants of the architectural

remodeling of the myocardium, this histopathological study of the dilated, postmortem

canine left ventricle secondary to rapid ventricular pacing or aortocaval fistula was

undertaken. Using the picrosirius-polarization technique to enhance collagen

birefringence, we sought to examine the structural integrity of the collagen matrix and

interstitium. In the dilated failing ventricle secondary to rapid pacing, we found 1)

interstitial edema and a disruption or disapearance of collagen fibers that were apparent

within 6 hours of pacing, persisted for weeks, and subsequently were associated with

muscle fiber disorganization within the endomyocardium, 2) interstitial fibrosis that was

present in the midwall and epimyocardium with chronic pacing, and 3) an early remodeling

of intramyocardial coronary arteries that included medial swelling with smooth muscle

degeneration followed by proliferative lesions involving fibroblasts and a subsequent

perivascular and medial fibrosis. Many of these findings were still evident 48 hours after

pacing had been discontinued. In contrast, the collagen matrix and interstitium seen with

ventricular dilatation secondary to the circulatory overload that accompanies an aortocaval

fistula were indistinguishable from that in sham-operated controls. Thus, we conclude that

unlike the chamber enlargement and preserved ventricular function that accompany an

aortocaval fistula, ventricular dilatation and failure caused by rapid pacing are based on an

architectural remodeling of the myocardium. This structural dilatation involves the

extracellular matrix and interstitium and appears to be related to altered permeability of

intramyocardial coronary arteries. The mechanism or mechanisms involved in the

pathogenesis of myocardial remodeling with rapid ventricular pacing require further

investigation (Au).

Au: Drake CJ; Davis LA; Walters L; Little CD.

Ad: Department of Anatomy and Cell Biology, University of Virginia, Charlottesville

22908.

Ti: Avian vasculogenesis and the distribution of collagens I, IV, laminin, and fibronectin in

the heart primordia.

So: J Exp Zool; 255(3):309-22, 1990 Sep.

Ab: The heart-forming regions of the early embryo are composed of splanchnic mesoderm,

endoderm, and the associated ECM. The ECM of the heart-forming regions in stage 7-9

chicken embryos was examined using immunofluorescence. Affinity purified antibodies to

chicken collagens type I and IV, chicken fibronectin, and mouse laminin were used as

probes. We report that (1) the basement membrane of the endoderm contains

immunoreactive laminin and collagen IV; (2) the nascent basement membrane of the heart

splanchnic mesoderm contains immunoreactive laminin, but not type IV collagen, and (3)

the prominent ECM between the splanchnic mesoderm and the endoderm (the primitive-

heart ECM) contains collagen IV, collagen I, fibronectin, but not laminin. In addition, we

describe microscopic observations on the spatial relationship of cardiogenic cells to the

primitive-heart ECM and the endodermal basement membrane (Au).

Au: Choy M; Armstrong MT; Armstrong PB.

Ad: Department of Pediatrics, University of California Davis Medical Center, Sacramento

95817.

Ti: Regulation of proliferation of embryonic heart mesenchyme: role of transforming

growth factor-beta 1 and the interstitial matrix.

So: Dev Biol; 141(2):421-5, 1990 Oct.

Ab: Proliferation of atrioventricular cushion mesenchyme of the embryonic avian heart

maintained in three-dimensional aggregate culture is stimulated by interaction with the

interstitial matrix. Chicken serum or transforming growth factor-beta 1, which timulates

proliferation, induces matrix deposition in regions of the aggregate showing high labeling

indices with tritiated thymidine. Dispersed heart mesenchyme interstitial matrix introduced

into serum-free culture is incorporated into the aggregate and stimulates cellular

proliferation similar to serum or transforming growth factor-beta 1. Proliferation is

reversibly inhibited by the peptide Gly-Arg-Gly-Asp-Ser-Pro. It is suggested that

transforming growth factor-beta 1 stimulates the production of interstitial matrix and that a

sufficient stimulus for proliferation in this system is the presence of the matrix, which

acts as the adhesive support for cellular anchorage (Au).

Au: Gruber BL; Schwartz LB.

Ad: Division of Allergy, Rheumatology and Clinical Immunology, Suny, Stony Brook

11794-8161.

Ti: The mast cell as an effector of connective tissue degradation: a study of matrix

susceptibility to human mast cells.

So: Biochem Biophys Res Commun; 171(3):1272-8, 1990 Sep 28.

Ab: The susceptibility of connective tissue elements to degradation by human mast cells

was explored using purified mast cell tryptase and sonicated mast cell preparations. The R-

22 strain of smooth muscle cells from rat heart was used for preparation in vitro of a

labelled anchored matrix. Digestion of 11.9 +/- 1.2% (n = 5) of this matrix was observed

after overnight incubation with the mast cell sonicates. Pretreatment of the sonicate with a

tryptase inhibitor TLCK reduced the digestion by 42%. Digestion of 12 +/- 1% (n = 4) of

the matrix was observed with purified tryptase. The susceptible substrate within this

anchored insoluble matrix resided in the glycoprotein compartment as defined by enzymatic

characterization of the residual matrix. Mast cells may play a role in mediating connective

tissue degradation through the release of proteases specifically synthesized by this cell (Au).

Au: Borg TK; Raso DS; Terracio L.

Ad: Department of Pathology, University of South Carolina, Columbia 29208.

Ti: Potential role of the extracellular matrix in postseptation development of the heart.

So: Ann N Y Acad Sci; 588:87-92, 1990.